Greatest common factor of 126

Evaluate the dot product of (3,-1) and (1,5)

Polygon mnopq is dilated by a scale factor of 0.8 with the origin as the center of dilation, resulting in the image m′n′o′p′q′. the coordinates of point m are (2, 4), and the coordinates of point n are (3, 5). the slope of is .

Which math sentence can be used to determine if the triangle is a right triangle?