Advertisements
Advertisements
Question
Find the value of x, if cos (2x – 6) = cos2 30° – cos2 60°
Advertisements
Solution
cos (2x – 6) = cos2 30° – cos2 60°
cos (2x – 6) = cos2 (90° – 60°) – cos2 60°
cos (2x – 6) = sin2 60° – cos2 60°
cos (2x – 6) = 1 – 2 cos2 60°
= `1 - 2(1/2)^2`
= `1 - 1/2`
= `1/2`
cos (2x – 6) = `1/2`
cos (2x – 6) = cos 60°
(2x – 6) = 60°
2x = 66°
Hence, x = 33°
APPEARS IN
RELATED QUESTIONS
If tan 2θ = cot (θ + 6º), where 2θ and θ + 6º are acute angles, find the value of θ
Prove the following trigonometric identities.
`((1 + cot^2 theta) tan theta)/sec^2 theta = cot theta`
Use tables to find the acute angle θ, if the value of cos θ is 0.6885
∠ACD is an exterior angle of Δ ABC. If ∠B = 40o, ∠A = 70o find ∠ACD.
If A + B = 90° and \[\cos B = \frac{3}{5}\] what is the value of sin A?
If \[\frac{x {cosec}^2 30°\sec^2 45°}{8 \cos^2 45° \sin^2 60°} = \tan^2 60° - \tan^2 30°\]
If A and B are complementary angles, then
If sin θ =7/25, where θ is an acute angle, find the value of cos θ.
Prove that:
(sin θ + 1 + cos θ) (sin θ − 1 + cos θ) . sec θ cosec θ = 2
Evaluate: `(cot^2 41°)/(tan^2 49°) - 2 (sin^2 75°)/(cos^2 15°)`
