Question

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Answer 1

#1

Use angle sum property

m<1

• 180-72-57
• 51°

#2

Angles are complementary

m<2

• 90-72
• 18°

#3.

Angles are supplementary

m<3

• 180-57
• 123°

#4.

Use angle sum property

m<4

• 180-123-18
• 39°

Answer 2

Useful for this exercise:

• Sum of interior angles of a triangle is 180°
• Straight angle is 180°
• Angle addition postulate

Finding missing angles:

• m∠1 = 180° - (57° + 72°) = 51°
• m∠2 = 90° - 72° = 18°
• m∠3 = 180° - 57° = 123°
• m∠4 = 180° - (18° + 123°) = 39°