Suppose the original quantity is $30 and the new quantity is $39 estimate the percent change is this an example of a percent increase or a percent decrease

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

The distance of a chord from the centre of a circle is 12cm and the lenght of the chord is 10cm. find the radius of the circle

Having a hard time understanding this question (see attachment).