Pre-Algebra

Lesson 7.6

Triangles

Triangles

Whadda ya know 'bout...

Review: Degrees of Angels

Less than 90o 90o degrees Greater than 90o

angles

Acute Right Obtuse

In every triangle, the sum of all the interior angles equal up to ______ degrees.

A

B

C

A B C

Finding the measure of an unknown angle

65o

45o

1

65o + 45o + m∠1 = 180o 110o + m∠1 = 180o

m∠1 = 70o

Your turn: What is m∠E?

Your turn: What is m∠A?

A

BC88o 37o

Your turn: What is x?

x + x + 140o = 180o

isosceles

138o

anglesAcute

Triangle

Right Triangle

All 3 angles are acute

Exactly one angle is right

Types of triangles

Obtuse

Triangle

Exactly one angle is obtuse

Classify these triangles

1. Dealer, give two students 2 cards each, and one student the missing angle card. **if no dealer, everyone choose your own cards. Rotate missing angle card.

1 3 5 7 ?

2. Missing angle card: find out your degree.

3. Known angles, figure out your degree.

13 + 57 + ? = 180

4. Rotate. Take turns being dealer/missing angle