Question

Angle ABC is formed by segments AB and BC on the following coordinate grid:
Angle ABC is rotated 90 degrees counterclockwise about the origin to form angle A′B′C′. Which statement shows the measure of angle A′B′C′?

a) m∠ A′B′C′ = 90 degrees
b) m∠ A′B′C′ = m∠ABC
c) m∠ A′B′C′ = 180 degrees
d) m∠ A′B′C′ = 2 ⋅ m∠ABC

Answer 1

the correct answer would be
b)
all your doing is rotating the whole thing, so you don't change the angle at all

Answer 2

Answer:

b. $m\angle ABC=m\angle A'B'C'$

Step-by-step explanation:

We are given that

Angle ABC is formed  by segments AB and BC on the following coordinate grid : A(1,-1), B(5,-4) and C(1,-4)

Angle ABC is rotated 90 degrees counterclockwise about the origin to form angle A'B'C'.

We have to find the measure of angle A'B'C'.

We know that when we rotate an angle then the measure of angle does not change. It remain same.

When we the angle ABC is rotated 90 degrees in counterclockwise about the origin then the coordinates of A ,B and C are changes, but not the measure of angle.

Therefore, the measure of angle A'B'C' is equal to measure of angle ABC.

Hence, $m\angle ABC=m\angle A'B'C'$

Therefore, option b is true.

Answer:b. $m\angle ABC=m\angle A'B'C'$