[求助]另一道prep2 的数学

What is the greatest possible area of a triangular region with one vertex at the center of a circle with radius 1 and the other two vetices on the circle?

答案: 1/2

想问下除了利用列一个关于三角函数的的式子求极值以外还有没有更好的方法了?

考场上解这种函数太麻烦了