Answer:
90°
Step-by-step explanation:
AB and CD are parallel lines and EF is reversal
Therefore angles BGH and DHG are consecutive interior angles
<u>As we know the sum of consecutive interior angles equals to 180°:</u>
<u>Line GP bisects angle BGH , therefore</u>
<u>Line HP bisects angle GHD, therefore</u>
<u>Sum of two angles of triangle GHP:</u>
- m∠PGH + m∠GHD = 1/2(∠BGH + ∠DHG) = 1/2*180° = 90°
<u>Therefore the missing angle a is:</u>
- ∠a = 180° - (m∠PGH + m∠GHD) = 180° - 90° = 90°