Question

Titik B(3, -2) dirotasikan sebesar 90° terhadap titik pusat P(-1, 1). Bayangan titik B adalah....
a. B'(-4, 3)
b. B'(-2, 1)
c. B'(-1, 2)
d. B'(1, 4)
e. B'(2, 5)

Answer 1

B(3,-2)
Rotasi 90° dg P(a,b) = (-1,1)

x' - a = -(y - b)
x' + 1 = -(-2 - 1)
x' = 3 - 1
x' = 2

y' - b = y - b
y' - 1 = -2 - 1
y' = -3 + 1
y' = -2

Bayangan : (2,-2)