Which definite integral gives the area of the region that lies insider=3cosθ and outsider=3sinθ in the first quadrant?
a) 21∫0π/4((3sinθ)2−(3cosθ)2)dθ
b) ∫0π/4((3cosθ)2−(3sinθ)2)dθ
c) 21∫0π/4((3cosθ)2−(3sinθ)2)dθ
d) 21∫0π/2((3cosθ)2−(3sinθ)2)dθ