Warm Up 10.31.11Week 3

State the number of sides:

1) Equilateral Triangle

2) Rhombus

3) Rectangular Prism

Geometry

4.1 Day 1

I will classify triangles by their sides and angles.

Triangle A figure formed by three segments joining three noncollinear points.

Acute Triangle

Equiangular Triangle

3 acute angles

3 congruent angles

Right Triangle

1 right angle

Obtuse Triangle 1 obtuse angle

Equilateral Triangle

Isosceles Triangle

3 congruent sides

at least 2 congruent sides

Scalene Triangle no congruent sides

∆ EFG is acute and . . .

Ex 1

E

F

G58⁰ 57⁰

65⁰

Rule 1

When describing be as specific as possible.

scalene.

Vertex The points joining the sides.

A

B

C

Points A,B, and C are vertices.

Adjacent Sides

Two sides sharing the same vertex.

and are adjacent to ∠B.

Opposite Side

The non-adjacent side.

is opposite to ∠B.

Isosceles Triangle Labels

The non-leg side.Base

The two congruent sides.

Leg leg

leg

base

An isosceles triangle with 3 congruent sides is an equilateral triangle.

Right Triangle Labels

hypotenuse The side opposite the right angle.

legs Sides that form the right angle.

hypotenuse

leg

leg

Triangle Sum Theorem

The sum of the measure of the interior angles of a triangle is 180⁰.

Theorem 4.1

A

B

C

m∠A + m∠B + m∠C = 180⁰

Do: 1

Assignment:

textbook Page 198, 10 - 32 evens

m∠C?

A

B

C

48⁰