関連ワード:  derivative of cot^2x    derivative of cot^2    derivative of cot^2x by first principle method    derivative of cot^2(sin x)    derivative of cot^2(2x)    derivative of cot 2x    derivative of cot 2    derivative of cot 2x by first principle method    derivative of cot 2 theta    derivative of cot 2 sinx