R is the region below the curve y=x and above the x-axis from x=0 to x=b; where b is a positive constant.

S is the region below the curve y=cos (x) and above the x-axis from x=0 to x=b. for what value of b is R equal in area to the area of S?

so I know this means $\displaystyle \int_0^bRdx = \int_0^bSdx$

So do I solve $\displaystyle \int xdx =\int cos(x)dx \Rightarrow \frac{x^2}{2} = sin (x)$ ?

If so I ge t 1.402