What is the coordinate of vertex A.

Question

. Maggie graphed the image of a 90 counterclockwise rotation about vertex A of( traingle ABC) . Coordinates B and C of (triangle ABC) are (2, 6) and (4, 3) and coordinates B’ and C’ of it’s image are (–2, 2) and (1, 4). What is the coordinate of vertex A.

Answer 1

Determine the point of intersection of the perpendicular bisectors.

Mid_BB' = (0, 4)

m_BB' = 1

Equation of perpendicular bisector: y = -x + 4

Mid_CC' = (5/2, 7/2)

m_CC' = -1/3

Equation of perpendicular bisector: y = 3x - 4

Solve the system of equations for the point of rotation.