find values of p and q for which `f(x) = {(1-sin^3x)/(3cos^2x)` , if `x lt pi/2` and `p`...

`f(x) = {(1-sin^3x)/(3cos^2x)` , if `x lt pi/2` and
`p` , if `x = pi/2` and `q (1-sinx) /(pi-2x)^2` if `x gt pi/2`
is continuous at `x = pi/2`