Question

sin a, если cosa=0,3 , a 0<x< п/2

Answer 1

$cos alpha =0,3\\0 textless alpha textless frac{pi}{2}; ; Rightarrow ; ; sin alpha textgreater 0\\sin^2 alpha =1-cos^2 alpha ; ; Rightarrow ; ; sin alpha =pm sqrt{1-cos^2 alpha }\\sin alpha =+sqrt{1-cos^2 alpha }=sqrt{1-(0,3)^2}=sqrt{0,91}$