Question

Evaluate: cos² 40º - cos² 50º​

Answer 1

Answer:

=cos80

Step-by-step explanation:

cos^2 40-cos^2 50

=cos^2 40-cos^2(90-40)

=cos^40-sin^2 40

=cos2*40

=cos80

Answer 2

Answer:

the correct answer is {cos (80)}