Which of the following graphs represent a function?

Which statement explains how you could use coordinate geometry to prove that quadrilateral abcd is a parallelogram? -5 -4 -3 -2 -1 t 1 2 3 4 prove that all sides are congruent and have slopes that are opposite reciprocals prove that segments ad and ab are congruent and parallel prove that opposite sides are congruent and have equal slopes prove that segments bc and cd are congruent and parallel

Provide all steps given to find the answer. simplify: 5(2x+9)²

What is the missing justification in the proof of the pythagorean identity below, sin^2x+cos^2x=1, using a right triangle?