Question

evaluate cos15° please answer me fast​

Answer 1

Step-by-step explanation:

To find this value we can use the fact, that we

know cos30(cos30=√32)cos30=cos2⋅15=cos215−sin215

On the other hand sin215+cos215=1,

so we can make a system of equations:

To simplify the notation I will use s for

sin15 and c for cos15{c2+s2=1c2−s2=√32

If we add both sides of the equations

we get:

2c2=2+√32c2=2+√34And

finally c=√2+√32

Hopes it help you♥️♥️