若3sina+cosa=0,则1/sin^2a+cos^2a= A.10/3 B.5/3 C.2/3 D.-2
问题描述:
若3sina+cosa=0,则1/sin^2a+cos^2a= A.10/3 B.5/3 C.2/3 D.-2
答
若3sina+cosa=0,则1/sin^2a+cos^2a= A.10/3 B.5/3 C.2/3 D.-2