The circumference of a circle changes from 20 to4 after a dilation. What was the scale factor of the dilation.

0.2

Step-by-step:

20(original) multiplied by ___= 4(new). Solve that by dividing by 20, and you get a scale factor of 0.2

according to the triangle sum theorem, all the angles in a triangle must add up to 180 degrees. if we know one angle is already 90, we do 180-90=90. the other 2 angles must add up to 90, exactly.

step-by-step explanation: