Trigonometry as taught is mostly about memorizing two lousy triangles, namely half a square and half an equilateral triangle. This one is half an equilateral triangle.
The respective opposite sides of the 30/60/90 triangle are in ratio
![1:√(3):2](https://img.qammunity.org/2019/formulas/mathematics/middle-school/pqcbu5cllsj05yo49t7j4ugk3gv2sp1zfr.png)
A sine of √3/2 is an opposite of √3 and a hypotenuse of 2, so opposite and hypotenuse of the 60 degree angle. (It's the mama bear, in the middle, just right.)
![\sin 60^\circ = (√(3))/(2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/3r1s2x2n4ge8r7mqksomhlc0dyt4n4l8ap.png)
In the end you just have memorize the two tired triangles of trig.