Types of Triangles
A triangle with all three sides of equal length.
equilateral triangle
The shortcut for triangle congruence using three corresponding sides
SSS
Angles that add up to 90 degrees
complementary angles
What is the missing angle
60 60 ?
60
Find x when we have vertical angles
150
10x + 40
x = 11
A triangle that has one angle greater than 90°
an obtuse triangle
The shortcut for triangle congruence using two sides and the included angle
SAS
Angles that add up to 180 degrees
Supplementary Angles
What is the missing angle
45 60 ?
75
Find x when we have complementary angles
50
2x
x = 20
A triangle with two sides of equal length
isosceles triangle
The shortcut for triangle congruence using two angles and the included side.
ASA
Angles opposite each other when two lines cross
Vertical angles
What is the missing angle?
35 73 ?
72
Find x when we have supplementary angles
3x
54
x = 42
A triangle with all angles less than 90°
an acute triangle
The shortcut for triangle congruence using two angles and a non-included side.
AAS
Angles that share a common side
Adjacent angles
What is the missing angle
24.5, 57.3 ?
98.2
Find x when we have vertical angles
x/6
40
x = 240
A triangle with all sides of different lengths
scalene triangle
The shortcut for triangle congruence using two sides and a non-included angle.
SSA
If two angles are both equal and supplementary, what is the measure of each angle?
90 degrees
What is the missing angle?
12.7 49.4 ?
117.9
Find x when we have supplementary angles
0.19x +53
0.06x + 40
x = 348