I can write and solve equations to find unknown angle measures.

Angle A figure formed by two rays with a common endpoint or vertex. The symbol ∠ means angle. When an m is placed in front it means “the measure of the angle”

Angle Measure Sums If the sum of two angle measures is 90°, the angles are complementary. If the sum of two angle measures is 180°, the angles are supplementary.

Adjacent Angles Share a vertex and a side but have no interior points in common. Ex: Angles 1 and 2 are adjacent.

Finding Supplements and Complements The Leaning Tower of Pisa Find each angle measure We know a straight line measures 180° 3x – 35 and 2x must be supplements So 3x – 35 + 2x = 180 x = 43 Substitute and the measures are 3(43) – 35 and 2(43) 94° and 86°

You try! Complementary means the sum is 90° m∠A + m∠B = 90 and m∠A = 5(m ∠B) 5(m ∠B) + m ∠B = 90 6(m ∠B) = 90 m ∠B = 15°

6.1 Continued

Vertical Angles Formed by two intersecting lines and are opposite each other. Vertical angles have equal measure. Angles with equal measure are congruent angles. EX: Angles 1 and 2 are vertical angles

Practice Find m∠2, m∠3, and m∠4 if we know that m∠1 = 25.7°

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Assignment All P.218 #7-19