What is the measure in degrees of angle 3

Its due ! write an equation in which the quadratic expression 2x^2-2x 12 equals 0. show the expression in factored form and explain what your solutions mean for the equation. show your work.

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

Which geometric principle is used to justify the construction below?