If straight sides of a triangular section of a lined canal with circular bottom of radius R, make an angle θ with horizontal, the area of its cross-section, is
A
R (θ + tan θ)
B
R (θ + cot θ)
C
R2 (θ + tan θ)
D
R2 (θ + cot θ)
Correct Answer: R2 (θ + cot θ)