Pythagorean theorem is

and using that sin is opposite/hypotenuse, you can find the third side of the triangle.

now you know adjacent is 60, so cos=60/61
7s = 4
/7. /7
s= 4/7
thats the equation right?
11 and 12
7 and 512
12 and 10
0 and 78
left side numerator
right side denominator