+50 A triangle with vertices A(3, -1), B(-2, 6), and C(5,4) is rotated 90° clockwise about vertex B. Find the co-ordinates of the image of vertex C.
+128631 Here's one way to do this...but not necessarily the fastest
Translate A to ( 3 + 2, - 1 - 6) = (5, - 7)
Rotating this 90° clockwise produces ( -7, - 5)
Now "undo" the translation....so we have ( -7 - 2, -5 + 6) = ( -9, 1)
Tranlate C to (5 + 2, 4 - 6) = (7, -2)
Rotating this 90° clockwise produces ( -2, - 7)
"Undo" the translation = ( -2 - 2 , -7 + 6) = (-4, -1)
Here's a pic :
