#### Chapters

Chapter 2: Profit , Loss and Discount

Chapter 3: Compound Interest

Chapter 4: Expansions

Chapter 5: Factorisation

Chapter 6: Changing the subject of a formula

Chapter 7: Linear Equations

Chapter 8: Simultaneous Linear Equations

Chapter 9: Indices

Chapter 10: Logarithms

Chapter 11: Triangles and their congruency

Chapter 12: Isosceles Triangle

Chapter 13: Inequalities in Triangles

Chapter 14: Constructions of Triangles

Chapter 15: Mid-point and Intercept Theorems

Chapter 16: Similarity

Chapter 17: Pythagoras Theorem

Chapter 18: Rectilinear Figures

Chapter 19: Quadrilaterals

Chapter 20: Constructions of Quadrilaterals

Chapter 21: Areas Theorems on Parallelograms

Chapter 22: Statistics

Chapter 23: Graphical Representation of Statistical Data

Chapter 24: Perimeter and Area

Chapter 25: Surface Areas and Volume of Solids

Chapter 26: Trigonometrical Ratios

Chapter 27: Trigonometrical Ratios of Standard Angles

Chapter 28: Coordinate Geometry

## Chapter 27: Trigonometrical Ratios of Standard Angles

### Frank solutions for Class 9 Maths ICSE Chapter 27 Trigonometrical Ratios of Standard Angles Exercise 27.1

Without using tables, evaluate the following: sin60° sin30°+ cos30° cos60°

Without using tables, evaluate the following: sec30° cosec60° + cos60° sin30°.

Without using tables, evaluate the following sec45° sin45° - sin30° sec60°.

Without using tables, evaluate the following: sin^{2}30° sin^{2}45° + sin^{2}60° sin^{2}90°.

Without using tables, evaluate the following: tan^{2}30° + tan^{2}60° + tan^{2}45°

Without using tables, evaluate the following: sin^{2}30° cos^{2}45° + 4tan^{2}30° + sin^{2}90° + cos^{2}0°

Without using tables, evaluate the following: cosec^{2}45° sec^{2}30° - sin^{2}30° - 4cot^{2}45° + sec^{2}60°.

Without using tables, evaluate the following: cosec^{3}30° cos60° tan^{3}45° sin^{2}90° sec^{2}45° cot30°.

Without using tables, evaluate the following: (sin90° + sin45° + sin30°)(sin90° - cos45° + cos60°).

Without using tables, evaluate the following: 4(sin^{4}30° + cos^{4}60°) - 3(cos^{2}45° - sin^{2}90°).

Without using tables, find the value of the following: `(sin30° - sin9° + 2cos0°)/(tan30° tan60°)`

Without using tables, find the value of the following: `(sin30°)/(sin45°) + (tan45°)/(sec60°) - (sin60°)/(cot45°) - (cos30°)/(sin90°)`

Without using tables, find the value of the following: `(tan45°)/("cosec"30°) + (sec60°)/(cot45°) - (5sin90°)/(2cos0°)`

Without using table, find the value of the following: `(tan^2 60° + 4cos^2 45° + 3sec^2 30° + 5cos90°)/(cosec30° + sec60° - cot^2 30°)`

Without using tables, find the value of the following: `(4)/(cot^2 30°) + (1)/(sin^2 60°) - cos^2 45°`

Prove that: sin60°. cos30° - sin60^{°}. sin30^{°} = `(1)/(2)`

Prove that : cos60° . cos30° - sin60° . sin30° = 0

Prove that : sec^{2}45° - tan^{2}45° = 1

Prove that: `((cot30° + 1)/(cot30° -1))^2 = (sec30° + 1)/(sec30° - 1)`

Find the value of 'A', if 2 cos A = 1

Find the value of 'A', if 2 sin 2A = 1

Find the value of 'A', if cosec 3A = `(2)/sqrt(3)`

Find the value of 'A', if 2cos 3A = 1

Find the value of 'A', if `sqrt(3)cot"A"` = 1

Find the value of 'A', if cot 3A = 1

Find the value of 'A', if (1 - cosec A)(2 - sec A) = 0

Find the value of 'A', if (2 - cosec 2A) cos 3A = 0

If sin α + cosβ = 1 and α= 90°, find the value of 'β'.

Solve for 'θ': `sin θ/(3)` = 1

Solve for 'θ': cot^{2}(θ - 5)° = 3

Solve for 'θ': `sec(θ/2 + 10°) = (2)/sqrt(3)`

Find the value of x in the following: 2 sin3x = `sqrt(3)`

Find the value of x in the following: `2sin x/(2)` = 1

Find the value of x in the following: `sqrt(3)sin x` = cos x

Find the value of x in the following: tan x = sin45° cos45° + sin30°

Find the value of x in the following: `sqrt(3)`tan 2x = cos60° + sin45° cos45°

Find the value of x in the following: cos2x = cos60° cos30° + sin60° sin30°

If sinθ = cosθ and 0° < θ<90°, find the value of 'θ'.

If tanθ= cotθ and 0°≤ θ ≤ 90°, find the value of 'θ'.

If `sqrt(2) = 1.414 and sqrt(3) = 1.732`, find the value of the following correct to two decimal places tan60°

If θ = 30°, verify that: tan2θ = `(2tanθ)/(1 - tan^2θ)`

If θ = 30°, verify that: sin2θ = `(2tanθ)/(1 ++ tan^2θ)`

If A = 30°, verify that cos2θ = `(1 - tan^2 θ)/(1 + tan^2 θ)` = cos^{4}θ - sin^{4}θ = 2cos^{2}θ - 1 - 2sin^{2}θ

If θ = 30°, verify that: sin 3θ = 4sinθ . sin(60° - θ) sin(60° + θ)

If θ = 30°, verify that: 1 - sin 2θ = (sinθ - cosθ)^{2}

Evaluate the following: `((sin3θ - 2sin4θ))/((cos3θ - 2cos4θ))` when 2θ = 30°

Evaluate the following: `((1 - cosθ)(1 + cosθ))/((1 - sinθ)(1 + sinθ)` if θ = 30°

If θ = 15°, find the value of: cos3θ - sin6θ + 3sin(5θ + 15°) - 2 tan^{2}3θ

If A = B = 60°, verify that: cos(A - B) = cosA cosB + sinA sinB

If A = B = 60°, verify that: sin(A - B) = sinA cosB - cosA sinB

If A = B = 60°, verify that: tan(A - B) = `(tan"A" - tan"B")/(1 + tan"A" tan"B"")`

If A = 30° and B = 60°, verify that: sin (A + B) = sin A cos B + cos A sin B

If A = 30° and B = 60°, verify that: cos (A + B) = cos A cos B - sin A sin B

If A = 30° and B = 60°, verify that: `(sin("A" + "B"))/(cos"A" . cos"B")` = tanA + tanB

If A = 30° and B = 60°, verify that: `(sin("A" -"B"))/(sin"A" . sin"B")` = cotB - cotA

If A = B = 45°, verify that sin (A - B) = sin A .cos B - cos A.sin B

If A = B = 45°, verify that cos (A - B) = cosA.cos B + sin A.sin B

If sin(A - B) = sinA cosB - cosA sinB and cos(A - B) = cosA cosB + sinA sinB, find the values of sin15° and cos15°.

If θ < 90°, find the value of: sin^{2}θ + cos^{2}θ

If θ < 90°, find the value of: `tan^2θ - (1)/cos^2θ`

If `sqrt(3)`sec 2θ = 2 and θ< 90°, find the value of θ

If `sqrt(3)` sec 2θ = 2 and θ< 90°, find the value of

cos 3θ

If `sqrt(3)` sec 2θ = 2 and θ< 90°, find the value of

cos^{2} (30° + θ) + sin^{2} (45° - θ)

In the given figure, PQ = 6 cm, RQ = x cm and RP = 10 cm, find

a. cosθ

b. sin^{2}θ- cos^{2}θ

c. Use tanθ to find the value of RQ

Find the value of: `sqrt((1 - sin^2 60°)/(1 + sin^2 60°)` If 3 tan^{2}θ - 1 = 0, find the value

a. cosθ

b. sinθ

If sin(A +B) = 1(A -B) = 1, find A and B.

If tan(A - B) = `(1)/sqrt(3)` and tan(A + B) = `sqrt(3)`, find A and B.

If sin(A - B) = `(1)/(2)` and cos(A + B) = `(1)/(2)`, find A and B.

In ΔABC right angled at B, ∠A = ∠C. Find the value of:

(i) sinA cosC + cosA sinC

(ii) sinA sinB + cosA cosB

If tan `"A" = (1)/(2), tan "B" = (1)/(3) and tan("A" + "B") = (tan"A" + tan"B")/(1 - tan"A" tan"B")`, find A + B.

### Frank solutions for Class 9 Maths ICSE Chapter 27 Trigonometrical Ratios of Standard Angles Exercise 27.2

Find the value of 'x' in each of the following:

Find the value of 'x' in each of the following:

Find the value of 'x' in each of the following:

Find the value of 'x' in each of the following:

Find the length of AD. Given: ∠ABC = 60°, ∠DBC = 45° and BC = 24 cm.

Find lengths of diagonals AC and BD. Given AB = 24 cm and ∠BAD = 60°.

In a trapezium ABCD, as shown, AB ‖ DC, AD = DC = BC = 24 cm and ∠A = 30°. Find: length of AB

Find the length of EC.

In the given figure, AB and EC are parallel to each other. Sides AD and BC are 1.5 cm each and are perpendicular to AB. Given that ∠AED = 45° and ∠ACD = 30°. Find:

a. AB

b. AC

c. AE

In the given figure, ∠B = 60°, ∠C = 30°, AB = 8 cm and BC = 24 cm. Find:

a. BE

b. AC

Find:

a. BC

b. AD

c. AC

Find the value 'x', if:

Find the value 'x', if:

Find the value 'x', if:

Find the value 'x', if:

Find the value 'x', if:

Find the value 'x', if:

Find the value of 'y' if `sqrt(3)` = 1.723.

Given your answer correct to 2 decimal places.

Find the value of 'y' if `sqrt(3)` = 1.723.

Given your answer correct to 2 decimal places.

In the given figure, if tan θ = `(5)/(13), tan α = (3)/(5)` and RS = 12m, find the value of 'h'.

Find x and y, in each of the following figure:

Find x and y, in each of the following figure:

If tan x° = `(5)/(12) . tan y° = (3)/(4)` and AB = 48m; find the length CD.

In a right triangle ABC, right angled at C, if ∠B = 60° and AB = 15units, find the remaining angles and sides.

If ΔABC is a right triangle such that ∠C = 90°, ∠A = 45° and BC =7units, find ∠B, AB and AC.

In a rectangle ABCD, AB = 20cm, ∠BAC = 60°, calculate side BC and diagonals AC and BD.

In right-angled triangle ABC; ∠B = 90°. Find the magnitude of angle A, if:

a. AB is `sqrt(3)` times of BC.

B. BC is `sqrt(3)` times of BC.

A ladder is placed against a vertical tower. If the ladder makes an angle of 30° with the ground and reaches upto a height of 18 m of the tower; find length of the ladder.

The perimeter of a rhombus is 100 cm and obtuse angle of it is 120°. Find the lengths of its diagonals.

In the given figure; ∠B = 90°, ∠ADB = 30°, ∠ACB = 45° and AB = 24 m. Find the length of CD.

In the given figure, a rocket is fired vertically upwards from its launching pad P. It first rises 20 km vertically upwards and then 20 km at 60° to the vertical. PQ represents the first stage of the journey and QR the second. S is a point vertically below R on the horizontal level as P, find:

a. the height of the rocket when it is at point R.

b. the horizontal distance of point S from P.

### Frank solutions for Class 9 Maths ICSE Chapter 27 Trigonometrical Ratios of Standard Angles Exercise 27.3

Evaluate the following: `(sin62°)/(cos28°)`

Evaluate the following: `(sec34°)/("cosec"56°)`

Evaluate the following: `(tan12°)/(cot78°)`

Evaluate the following: `(sin25° cos43°)/(sin47° cos 65°)`

Evaluate the following: `(sec32° cot26°)/(tan64° "cosec"58°)`

Evaluate the following: `(cos34° cos35°)/(sin57° sin56°)`

Evaluate the following: sin31° - cos59°

Evaluate the following: cot27° - tan63°

Evaluate the following: cosec 54° - sec 36°

Evaluate the following: sin28° sec62° + tan49° tan41°

Evaluate the following: sec16° tan28° - cot62° cosec74°

Evaluate the following: sin22° cos44° - sin46° cos68°

Evaluate the following: `(sin36°)/(cos54°) + (sec31°)/("cosec"59°)`

Evaluate the following: `(tan42°)/(cot48°) + (cos33°)/(sin57°)`

Evaluate the following: `(2sin28°)/(cos62°) + (3cot49°)/(tan41°)`

Evaluate the following: `(5sec68°)/("cosec"22°) + (3sin52° sec38°)/(cot51° cot39°)`

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: sin65° + cot59°

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: cos72° - cos88°

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: cosec64° + sec70°

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: tan77° - cot63° + sin57°

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: sin53° + sec66° - sin50°

Express each of the following in terms of trigonometric ratios of angles between 0° and 45°: cos84° + cosec69° - cot68°

Evaluate the following: sin35° sin45° sec55° sec45°

Evaluate the following: cot20° cot40° cot45° cot50° cot70°

Evaluate the following: cos39° cos48° cos60° cosec42° cosec51°

Evaluate the following: sin(35° + θ) - cos(55° - θ) - tan(42° + θ) + cot(48° - θ)

Evaluate the following: tan(78° + θ) + cosec(42° + θ) - cot(12° - θ) - sec(48° - θ)

Evaluate the following: `(3sin37°)/(cos53°) - (5"cosec"39°)/(sec51°) + (4tan23° tan37° tan67° tan53°)/(cos17° cos67° "cosec"73° "cosec"23°)`

Evaluate the following: `(sin0° sin35° sin55° sin75°)/(cos22° cos64° cos58° cos90°)`

Evaluate the following: `(2sin25° sin35° sec55° sec65°)/(5tan 29° tan45° tan61°) + (3cos20° cos50° cot70° cot40°)/(5tan20° tan50° sin70° sin40°)`

Evaluate the following: `(3sin^2 40°)/(4cos^2 50°) - ("cosec"^2 28°)/(4sec^2 62°) + (cos10° cos25° cos45° "cosec"80°)/(2sin15° sin25° sin45° sin65° sec75°)`

Evaluate the following: `(5cot5° cot15° cot25° cot35° cot45°)/(7tan45° tan55° tan65° tan75° tan85°) + (2"cosec"12° "cosec"24° cos78° cos66°)/(7sin14° sin23° sec76° sec67°)`

If cos3θ = sin(θ - 34°), find the value of θ if 3θ is an acute angle.

If tan4θ = cot(θ + 20°), find the value of θ if 4θ is an acute angle.

If sec2θ = cosec3θ, find the value of θ if it is known that both 2θ and 3θ are acute angles.

If sin(θ - 15°) = cos(θ - 25°), find the value of θ if (θ-15°) and (θ - 25°) are acute angles.

If A, B and C are interior angles of ΔABC, prove that sin`(("A" + "B")/2) = cos "C"/(2)`

If P, Q and R are the interior angles of ΔPQR, prove that `cot(("Q" + "R")/2) = tan "P"/(2)`

If cosθ = sin60° and θ is an acute angle find the value of 1- 2 sin^{2}θ

If secθ= cosec30° and θ is an acute angle, find the value of 4 sin^{2}θ - 2 cos^{2}θ.

Prove the following: tanθ tan(90° - θ) = cotθ cot(90° - θ)

Prove the following: sin58° sec32° + cos58° cosec32° = 2

Prove the following: `(tan(90° - θ)cotθ)/("cosec"^2 θ)` = cos^{2}θ

Prove the following: sin^{2}30° + cos^{2}30° = `(1)/(2)sec60°`

If A + B = 90°, prove that `(tan"A" tan"B" + tan"A" cot"B")/(sin"A" sec"B") - (sin^2"B")/(cos^2"A")` = tan^{2}A

## Chapter 27: Trigonometrical Ratios of Standard Angles

## Frank solutions for Class 9 Maths ICSE chapter 27 - Trigonometrical Ratios of Standard Angles

Frank solutions for Class 9 Maths ICSE chapter 27 (Trigonometrical Ratios of Standard Angles) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Class 9 Maths ICSE solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Maths ICSE chapter 27 Trigonometrical Ratios of Standard Angles are Trigonometric Equation Problem and Solution, Trigonometric Ratios of Some Special Angles, Trigonometric Ratios of Some Special Angles, Trigonometric Ratios of Some Special Angles.

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