The value of angle 3 in the quadrilateral is determined as m∠ 3 = 84⁰. (Option C).
How to calculate the value of angle 3?
The value of angle 3 is calculated by applying the following principle for a quadrilateral with two equal opposite sides.
In the given shape, based on the markings, we can see that the base angles are congruent (equal).
The missing base angle of the quadrilateral is calculated as follows;
m∠1 = 96⁰
Also the value of the remaining two sides of the quadrilateral is calculated as follows;
m ∠ 2 + m ∠ 3 = 360 - (96 + 96) (sum of angles of a quadrilateral)
m ∠ 2 = m ∠ 3
m ∠ 3 + m ∠ 3 = 360 - (96 + 96)
2m∠ 3 = 360 - (192)
2m∠ 3 = 168
m∠ 3 = 168 / 2
m∠ 3 = 84⁰