Question

已知tan a/2=根号3/3 求sin^2a+(cos a/2)^2的值

Answer 1

答：

tan(a/2)=√3/3

tan²(a/2)=(1-cosa)/(1+cosa)=1/3

解得：cosa=1/2

sin²a+cos²(a/2)

=1-cos²a+(cosa+1)/2

=1-1/4+(1/2+1)/2

=3/2