Step-by-step explanation:
17.
by Angle Sum Property
21⁰ + 31⁰ + ?⁰ = 180⁰
?⁰ = 180 - 52⁰
?⁰ = 128⁰
12.
<F + < V = 90⁰ ( Complementary )
29⁰ + <V = 90⁰
<V = 61⁰
Answer:
17: 128
12: 61
22: regular hexagon
23: heptagon
17: 31 + 21 = 52. 180 - 52 = 12812: 90 - 29 = 6122: a hexagon has 6 sides, and this hexagon is a normal one23: heptagons have 7 sides and this has 7 sides
