Question

θ第二象限角 根号下sin^2θ-sin^4θ可化简为

Answer 1

√(sin^2θ-sin^4θ)

=√((sinθ)^2(1-(sinθ)^2))

=√(sinθcosθ)^2

=|sinθcosθ|

因为θ在第二象限,所以sinθ>0,cosθ