Question

When triangle XYZ where X (-4,-3), Y (6, -1), and Z (7, 8) is rotated 90º clockwise about the origin, what is the new location?
A. triangle X�Y�Z� where X� (-3, 4), Y� (-1, -6), and Z� (8, -7)
B. triangle X�Y�Z� where X� (-3, -4), Y� (-1, 6), and Z� (8, 7)
C. triangle X�Y�Z� where X� (3, - 4), Y� (1, 6), and Z� (-8, 7)
D. triangle X�Y�Z� where X� (3, 4), Y� (1, -6), and Z� (-8, -7)

Answer 1

to rotate a point by some angle alpha:

X = x cos(a) - y sin(a)
Y = x sin(a) - y cos(a)

since a = 90 in this case

X = - y
Y = x