Types of Triangles
Formulas and Theorems
Congruence
Isosceles and Equilateral
Grab Bag
100

A triangle with an angle that measures more than 90

Obtuse

100

The angles in a triangle add to this

180

100

Three sides from one triangle are congruent to the three sides of the other

SSS

100

The angles in an equilateral triangle

60 degrees

100

The first reason of every proof

GIVEN

200

The type of triangle with angle measures 70, 80, 30

Acute

200

This angle is equal to the sum of the two remote interior angles

Exterior angle

200

I have two triangles with corresponding congruent angles and the side NOT between them

AAS

200

Congruent sides opposite

Congruent angles

200

Allows us to go from congruent to equal and equal to congruent

Def of Congruence

300

A regular triangle is both of these

Equilateral and Equiangular

300

A triangle can only have one of these two types of angles

Obtuse or right

300

When there are two pairs of congruent sides and the included angle

SAS

300

Congruent angles opposite

congruent sides

300

A triangle has 3 of each of these

sides and angles

400

This type of triangle has two angles with the same measure. Name by sides.

Isosceles

400

How can we prove that a triangle is scalene

Distance formula coordinate proof

400

I have two right triangles with congruent legs

LL

400

The vertex of an isosceles triangle is located where in relation to the other points

the middle

Midpoint

400

These form right angles

Perpendicular Lines

500

The triangle based on sides with angle measures 65, 35, 80

Scalene

500

We use this formula to show that a triangle is a right triangle

slope formula

500

This shortcut is used when we have two pairs of congruent sides and then an angle as we go around the triangle. Oh yeah, its right!

HL

500

The acute angles in this isosceles right triangle will always be this

45 degrees

500

What does CPCTC stand for

corresponding parts of congruent triangle are congruent