Maths
posted by Shym on .
Hi, can someone give me the answer to this question:
secAtanA=1/4. Find cosA
I got: CosA=4(1sinA) Is my answer good?
Now multply each side by (1+sinA)
CosA(1+sinA)=4 cos^2 A
CosA=1/4 (1+sinA)
16(1sinA)=1+sinA
15=17SinA
So you have sinA, now find Cos A from your equation you originally solved.

Cos A= 4(1(15/17))
cos A= 4(12/17)
Cos A= 48/17