Angle abc is formed by segments ab and bc on the following coordinate grid: a coordinate grid is shown from positive 6 to negative 6 on the x axis and from positive 6 to negative 6 on the y axis. a line segment ab is shown with a as ordered pair 1, negative 1 and b as ordered pair 5, negative 4. another line segment bc is shown with c as ordered pair 1, negative 4. 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′? m∠ a′b′c′ = 90 degrees m∠ a′b′c′ = m∠abc m∠ a′b′c′ = 180 degrees m∠ a′b′c′ = 2 ⋅ m∠abc