Question

Matching equations with diagrams & finding unknown angles #3

Which equation(s) and angle measurements go with the
diagram. Choose ALL that apply.
Find the value of a.
(Select all that apply.)

please help

Answer 1

Answer: a+51=90, a+51+90=180, 39

Explanation:

a+51=90 works because the angles add to form a right angle.

a+51=180 does not work because the angles add to form a right angle, not a straight angle.

a+51+90=180 works because all those angles add to form a straight angle.

a+90=180 does not work because the unknown in this situation refers to a+51, not just a.

Solving the equation, we get a=39, so 39 is also an answer.