Question

若cota=1/3则1/（seca*csca）=?

Answer 1

∵sec a=1/cot a,csc a=1/sin a

∴1/(sec a*csc a)=sin a cot a =(sin a)/3

∵sin a = ±Sqrt(1- (cot a)^2) = ±2/3*sqrt(2) (注：正负根下1减cot方,SQRT为开平方,是Excel中的函数用法)

∴1/(sec a*csc a) =(sin a)/3 =±2/9*sqrt(2)