What is the 45-45-90 right angle

Need ! give step by step solutions on how to solve number one \frac{9-2\sqrt{3} }{12+\sqrt{3} } number two x+4=\sqrt{13x-20} number three (domain and range) f(x)=2\sqrt[3]{x} +1

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

Write the point-slope form of the line passing through (2, -12) and parallel to y=3x.