Question

find the value of cos^2 15°+ cos^2 25°+cos^2 65°+cos^75°.
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Answer 1

Answer:

Answer = 2

Step-by-step explanation:

cos^2(15)= sin^2(90-15)

= sin^2(75)

cos^2(25)= sin^2(90-25)

= sin^2(65)

putting the values of cos^2(15) and cos^2(25) from above equations in the question, we get:-

cos^2( 15) +cos^2 (25) + cos^2(65) + cos^2(75)=

sin^2(75) + sin^2(65) + cos^2(65) + cos^2(75)=

trigonometric identity (cos^2theta + sin^2 theta = 1)

sin^2(75) + cos^2(75) + cos^2(65) + sin^2(65)= 2

the answer is 2

Answer 2

Answer:

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