Page 42 - Math Course 2 (Book 2)

Lines and Angles

MO. 8 - L1b supplementary angles
If the sum of the measures of two angles is 180°,
the angles are supplementary.
Relationships in Angles

m∠1 = 140°, m∠2 = 40°
Vocabulary A-Z m∠1 + m∠2 = 180°

Let us learn some vocabulary 1 2

vertical angles perpendicular lines

When two lines intersect, they form two pairs of Lines that intersect to form a right angle are
opposite angles called vertical angles. perpendicular lines.

∠3 and ∠4 are vertical ∠1 and ∠2 are vertical
angles. angles.
∠3 ≅ ∠4 ∠1 ≅ ∠2 right angle

3
1 2

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adjacent angles
When two angles have the same vertex, share a Let’s Begin
common side, and do not overlap, they are
adjacent angles.

B Real World Example
m∠A0B = m∠1 + m∠2
LEG LIFTS
∠1 and ∠2 are
adjacent Kian does leg lifts each morning. For each
A 1 2 angles. repetition he lifts his legs 35 degrees off the
0 ground. What is the measure of the angle
formed by his body and legs in this position?

The angles are supplementary.
complementary angles
If the sum of the measures of two angles is 90°, x + 35 = 180 Write the equation.
the angles are complementary.
x + 35 – 35 = 180 – 35 Subtract 35 from each
side.
x = 145 Simplify.

m∠1 = 50°, m∠2 = 40° The angle formed by his body

1 m∠1 + m∠2 = 90° Answer and legs is 145°.
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