Question

If m Subject geometry
Angle pairs

Answer 1

the angles are supplementary meaning they equal 180 degrees so 100-x=180

x=80

Answer 2

ANSWER

$m \angle ACE = 80 \degree$

EXPLANATION

Recall that adjacent angles on a straight line will add up to 180°

From the diagram, m<ACD and m<ACE are adjacent angles on a straight line because they have a common vertex at C.

We sum the two angles and equate them to 180°

$m \angle \: ACD + m \angle ACE = 180 \degree$

From the diagram

$m\angle ACD= 100 \degree$

We substitute the known angle to obtain:

$100 \degree + m \angle ACE = 180 \degree$

$m \angle ACE = 180 \degree - 100 \degree$

$\therefore \: m \angle ACE = 80 \degree$