Find the area of the region that bounded by the given curve and lies in the specified sector

a. Find the area of the region that bounded by the given curve and lies in the specified sector r=e−θ/6,π/2≤θ≤π
b. Find the area of the shaded region r=√θ,0≤θ≤2π.
c. Find the area of the shaded region r=4+3sinθ,−π/2≤θ≤π/2