+28 A triangle with vertices A(-2,-1),B(-1,4)and C(5,0) is rotated 90 ̊ counter clockwise about vertex B. Find the Co-ordinates of the image of vertex X
+128408 For ease, move B to the origin
Then A becomes ( -2 + 1 , -1 -4) = ( -1 , -5)
The 90° counterclock-wise rotation rule is x , y → -y , x
So the new point for the provisional "A" becomes (5, -1)
And A' becomes (5 - 1, -1 + 4) = (4, 3)
Likewise... C becomes ( 5 + 1, 0 -4) = (6,-4)
And the new point for provisional "B" becomes (4, 6)
And C' becomes ( 4 -1, , 6 + 4) = ( 3 , 9)
