Question

Evaluate cos 75degree + cos 15 degree

Answer 1

Explanation:

i hope it helps you......

Answer 2

$\huge\boxed{Hey\:Mate!!}$

cos75° + cos15°

= cos (45° + 30°) + cos (45°-30°)

NOTE:-

• cos(A+B)=cosA.cosB -sinA.sinB
• cos (A-B)=cosA.cosB +sinA.sinB

now, coming to the Question

=(cos45°. cos 30° - sin 45° + sin 30°) +

( cos 45°.cos30°+ sin45°+sin30°)

= 2cos45°.cos30°

=2.(1/√2).(√3/2)

=√6/2

Hope it helps!! ☺️