Question

the value of cos square 5 + cos square 10 + cos square 15........cos square 90​

Answer 1

Answer:

The answer is 1/4

Step-by-step explanation:

cos square 5 + cos square 10 + cos square 15........cos square 90​

= cos^2 120

We know cos 120 is -1/2

So cos^ 120= (-1/2)^2 = 1/4

Hope the answer helps!