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Prove the identity
I NEED TO KNOW FAST AS POSSIBLE

Prove the identity I NEED TO KNOW FAST AS POSSIBLE-example-1
User CEH
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1 Answer

5 votes

Answer:

see explanation

Explanation:

Using the trigonometric identities

sin²Θ = 1 - cos²Θ , cos²Θ = 1 - sin²Θ

Consider the left side

(sinΘ + cosΘ)(1 - sinΘcosΘ) ← distribute

= sinΘ(1 - sinΘcosΘ) + cosΘ(1 - sinΘcosΘ)

= sinΘ - sin²ΘcosΘ + cosΘ - sinΘcos²Θ

= sinΘ - (1 - cos²Θ)cosΘ + cosΘ - sinΘ(1 - sin²Θ)

= sinΘ - cosΘ + cos³Θ + cosΘ - sinΘ + sin³Θ ← collect like terms

= sin³Θ + cos³Θ

= right side ⇒ proven

User Wei Li
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