Question

若(sina)^2+2(sinb)^2=2cosa,y=(sina)^2+(sinb)^2的最大值为M,最小值为m,则M

Answer 1

(sin b)^2=[2cosa-(sin a)^2]/2

=[2cos a-(sin a)^2]/2

=[2cos a-1+(cos a)^2]/2

=[(cos a+1)^2-2]/2.

因为0