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Cosec^4θ + cosec^2θ = cot^4θ + cot^2θ - Mathematics

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Questions

cosec4 θ − cosec2 θ = cot4 θ + cot2 θ

Prove the following:

cosec4 θ − cosec2 θ = cot2 θ + cot4 θ

Theorem
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Solution 1

LHS = cosec4 θ − cosec2 θ

LHS = cosec2 θ (cosec2 θ − 1)

LHS = (cot2 θ + 1)cot2 θ     ...`{(cot^2 θ + 1 = cosec^2 θ),(∵ cot^2 θ = cosec^2 θ - 1):}`

LHS = cot4 θ + cot2 θ

RHS = cot4 θ + cot2 θ

RHS = LHS 

Hence proved.

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Solution 2

RHS = cot4 θ + cot2 θ

RHS = cot2 θ (cot2 θ + 1) 

RHS = (cosec2 θ − 1)cosec2 θ  ...`{(cot^2 θ + 1=cosec^2 θ),(∵ cot^2θ = cosec^2 θ - 1):}`

RHS = cosec4 θ − cosec2 θ

LHS = cosec4 θ − cosec2 θ

RHS = LHS 

Hence proved.

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Chapter 8: Trigonometric Identities - Exercises 1

APPEARS IN

R.S. Aggarwal Mathematics [English] Class 10
Chapter 8 Trigonometric Identities
Exercises 1 | Q 17.3
Nootan Mathematics [English] Class 10 ICSE
Chapter 18 Trigonometric identities
Exercise 18A | Q 5. | Page 423

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