The seven inner triangles in the picture are isosceles, as is the outer triangle. What is the measure of angle 21? Justify your response with work shown. helppp lol

Suppose a least-squares regression line is given by modifyingabove y with caret equals 4.302 x minus 3.293. what is the mean value of the response variable if xequals20?

Jose predicted that he would sell 48 umbrellas. he actually sold 72 umbrellas. what are the values of a and b in the table below? round to the nearest tenth if necessary

Me complete this proof! prove that a quadrilateral is a square. me with the steps for this proof.