Question

evaluate sin25 cos65 - cos 25 sin65​

Answer 1

Answer:

Step-by-step explanation:

sin25 cos65 - cos 25 sin65

=sin25 cos(90-25) -cos25sin(90-25)

sin25 sin25 - cos 25 cos25

=sin^2 25-cos^2 25

=sin^2 25-(1-sin^2 25)

2Sin^2 25-1

Answer 2

Step-by-step explanation:

sin25cos65 - cos25sin65

sin(90-65)cos65 - cos(90-65)sin65

cos65cos65 - sin65 sin65

cos^2 65 - sin^2 65

cos^2 65 -(1-cos^2 65)

cos^2 65 -1 + cos^2 65

2cos^2 65 - 1