Question

evaluate sin 25 cos 65 + cos 25 sin 65 = ?

Answer 1

sin 25° cos 65° + cos 25° sin 65°
= sin 25° cos (90-25) + cos 25° sin(90-25)
= sin 25° sin 25° + cos 25° cos 25°
= sin²25° + cos²25°
= 1 [sin²A+cos²A = 1]

Answer 2

Hello!

===================================

we need a formula which is

sin( A + B ) = sinAcosB + cosAsinB

Given us,

sin25cos65 + cos25sin65

= sin( 25 + 65 )

= sin90

= 1

thanks

===================================