Question

Find the value of Cos10-sin10

Answer 1

Hi ,

This is related to trigonometric transformations
_______________________________
We know that ,

i ) cos ( 90 - A ) = sin A

ii ) sin C - Sin D = 2cos( C + D )/2 × sin(C - D )/2

____________________________________

Cos 10 - sin 10

= cos (90-80) - sin10

= sin80 - sin10

= 2cos(80+10)/2×sin(80-10)/2

= 2cos45sin35

= 2 × ( 1/sqrt2) sin35

= ( sqrt2 × sqrt2 )/ ( sqrt2 ) × sin35

= ( sqrt 2) × sin35

I hope this helps you.

:)

Answer 2

the answer is attached hope that it helps