Classifying Triangles Add the following to your math notes.

The sum of the angle measures of EVERY triangle is 180°.

180°

Find the value of x x

Find the value of x 28° x° 135°

Find the value of x 36° 79° x°

Find the value of x 45° x°

Every triangle can be classified by its angles and by its sides.

Classifying Triangles by Angles

If EVERY angle is less than 90°, it is an ACUTE Triangle.

one is fat If the measure of ONE angle is more than 90° it’s an OBTUSE triangle.

all the same If the measure of EACH angle is equal, it is EQUIANGULAR.

If ONE angle measures 90°,

it is a RIGHT triangle.

Classifying Triangles by Sides

it is SCALENE. No sides the same If none of the sides have the same length,

it is an ISOSCELES triangle. If at least two sides measure the same,

Try to think of an isosceles triangle as a person.

The arms would be attached on the congruent sides.

The point shared by the congruent sides is the head.

The two other points represent the feet.

The angles by the “feet” are always congruent.

Try to figure out which angles are equal.

Be careful, your triangle might be “tired”.

all the sides equal EQUILATERAL. If the measure of EACH side is equal, it is…

All equilateral triangles are also equiangular.

Can a triangle be right and isosceles? What is the measure of the other 1 two angles? 2

A. 45°

B. 60°

C. 50° 65°

D. 28° 17° 135°

E. 36° 79° 65°

F. 41° 68° 71°

G. 25° 100° 55°

H. 120° 30°