Unit Review: Triangles

S.1A triangle's angles add up to 180°.

1. 1
   Find the missing angle. 
2. 2
   Find the missing angle. 
3. 3
   Find the missing angle. 
4. 4
   Find the missing angle. 

S.2Find the missing angle. Then write acute, right, or obtuse.

1. 5
   Find the missing angle. Acute, right, or obtuse? 
2. 6
   Find the missing angle. Acute, right, or obtuse? 

S.2Find the missing angle. Then write acute, right, or obtuse. (continued)

1. 7
   Find the missing angle. Acute, right, or obtuse? 
2. 8
   Find the missing angle. Acute, right, or obtuse? 

S.3Write equilateral, isosceles, or scalene.

1. 9
   Equilateral, isosceles, or scalene? 
2. 10
   Equilateral, isosceles, or scalene? 
3. 11
   Equilateral, isosceles, or scalene? 
4. 12
   Equilateral, isosceles, or scalene? 

S.4A square marks a 90° angle.

1. 13
   Find the missing angle. 
2. 14
   Find the missing angle. 
3. 15
   Find the missing angle. 
4. 16
   Find the missing angle. 

S.5Ticks mark equal sides. The angles opposite equal sides are equal.

1. 17
   The triangle is isosceles. Find each base angle. 
2. 18
   The triangle is isosceles. Find each base angle. 

S.5Ticks mark equal sides. The angles opposite equal sides are equal. (continued)

1. 19
   The triangle is isosceles. Find each base angle. 
2. 20
   The triangle is isosceles. Find each base angle. 

S.6A triangle's angles add up to 180°. A square marks a 90° angle; ticks mark equal sides.

1. 21
   Find the missing angle. Acute, right, or obtuse? 
2. 22
   Find the missing angle. Acute, right, or obtuse? 
3. 23
   Find the missing angle. Acute, right, or obtuse? 
4. 24
   Find the missing angle. Acute, right, or obtuse? 

S.1Find the Missing Angle

1. 1$20^{\circ }$
2. 2$55^{\circ }$
3. 3$115^{\circ }$
4. 4$55^{\circ }$

S.2Classify Triangles by Angles

1. 5$70^{\circ }$, acute
2. 6$25^{\circ }$, acute
3. 7$20^{\circ }$, obtuse
4. 8$40^{\circ }$, acute

S.3Classify Triangles by Sides

1. 9scalene
2. 10isosceles
3. 11scalene
4. 12scalene

S.4Missing Angle in a Right Triangle

1. 13$20^{\circ }$
2. 14$15^{\circ }$
3. 15$25^{\circ }$
4. 16$55^{\circ }$

S.5Base Angles of Isosceles Triangles

1. 17$60^{\circ }$
2. 18$25^{\circ }$
3. 19$65^{\circ }$
4. 20$80^{\circ }$

S.6Triangle Angles & Classification

1. 21$20^{\circ }$, acute
2. 22$47^{\circ }$, right
3. 23$13^{\circ }$, obtuse
4. 24$38^{\circ }$, right