题目

Here are some red and green (apple). 答案：【1】apples17．若$sinθ=\frac{3}{5}$，且θ是第二象限角，则cosθ=（　　）A．$-\frac{4}{5}$B．$\frac{4}{5}$C．$-\frac{3}{4}$D．$\frac{3}{4}$