Paul M. answered 05/25/20
Learn "how to" do the math and why the "how to" works!
There are several facts which will help you to answer this question.
1> In a 30-60 right triangle the ratio of the sides is 2:1:√3.
2> In an isosceles right triangle the ratio of the sides is 1:1:√2.
3> AllSinTanCos is a mnemonic to remember which trig functions are positive in which quadrant.