Question

The value of cos80°cos10°-sin80°sin10°

Answer 1

Answer:

0

Step-by-step explanation:

cos80cos10 - sin80sin10

= cos (90 - 10) . cos 10 - sin (90 - 10) . sin 10

= sin 10 . cos 10 - cos 10 - sin 10

= sin 10. cos 10 - sin 10 . cos 10

= 0

Property:

sin x = cos (90 - x)

cos x = sin (90 - x)

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Answer 2

Answer:

0

Step-by-step explanation:

cosx=sin(90-x)

therefore,

cos80cos10-cos10cos80 = 0