PROVE : sin^2(-300°).cos^2 (120)+ cos^2(-240 ).sin^2(390)=1/4

asked Apr 6, 2023 155k views

13 votes

PROVE :

sin^2(-300°).cos^2 (120)+ cos^2(-240 ).sin^2(390)=1/4

by Mrc

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9 votes

Explanation:

$\sin {}^(2) ( - 300) \cos {}^(2) (120) + \cos {}^(2) ( - 240) \sin {}^(2) (390) = (1)/(4)$

$\sin {}^(2) (60) \cos {}^(2) ( {}^{} 120) + \cos {}^(2) (120) \sin {}^(2) (30)$

(3)/(4) (1)/(4) + (1)/(4) (1)/(4)

(3)/(16) + (1)/(16) = (4)/(16) = (1)/(4)

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