Question

The value of sin-1(cos 13pi/5) is

a)-3pi/5 b) -pi/10 c) 3pi/5 d) pi/10

Answer 1

The value of sin-1(cos 13pi/5) is b) -pi/10

Comments

pls give me step by step solution

Answer 2

jawaan2720, hello again

The straightforward approach here, and most problems when you have an inverse trig function, is to convert to have the inverse trig operator on the trig function because then they just cancel each other out.  In other words:

The arcsine (sin^-1) is the inverse function to the sine function, therefore sin^-1(sin(x)) = x

So what you need to do now is convert cos(13pi/5) to an equivalent sine expression.

I hope this helps...