This math topic focuses on determining the relationships between angles in triangles, specifically within the context of geometry involving isosceles and equilateral triangles. It challenges students to use the triangle angle sum rule, where the total degrees in a triangle sum up to 180 degrees, to identify correct angle relationships and solve for missing angles, denoted by variables like x, y, z, b, d, n, and m. Each question presents a triangle with some angle values given and asks the student to identify the correct statement about the sum of the angles or the relationship between them.
Work on practice problems directly here, or download the printable pdf worksheet to practice offline.
Practice:
Rule for a Missing Angle on the Triangle
Complete these online problems with 80% or 4 correct answers in a row. Results are immediate.
What is known about the angles labelled 60, 40, d
Rule for a Missing Angle on the Triangle Worksheet
| Math worksheet on 'Rule for a Missing Angle on the Triangle (Level 1)'. Part of a broader unit on 'Geometry - Isosceles and Equilateral Triangles' Learn online: app.mobius.academy/math/units/geometry_triangles_isosceles_equilateral_intro/ |
| What is known about the angles labelled 75, 48, c |
| Nothing, 75, 48, and c are not related by any geometry rule |
| 75, 48, and c add up to 180° |
| 75 and 48 add to twice c |
| 75, 48, and c add up to 360° |
| 75 and 48 add to c |
| 75, 48, and c add up to 90° |
| What is known about the angles labelled 40, 60, y |
| 40, 60, and y add up to 90° |
| 40, 60, and y add up to 180° |
| y and 60 add to 40 |
| 40, 60, and y add up to 360° |
| 40 and 60 add to y |
| 40 is the same as 60 |
| What is known about the angles labelled 30, 50, x |
| x and 50 add to 30 |
| 30 is the same as 50 |
| 30, 50, and x add up to 180° |
| 30 and 50 add to twice x |
| 30 is half 50 |
| 30, 50, and x add up to 360° |
| What is known about the angles labelled 60, 40, z |
| 60, 40, and z add up to 360° |
| Nothing, 60, 40, and z are not related by any geometry rule |
| 60, 40, and z add up to 180° |
| 60 and 40 add to twice z |
| 60 is the same as 40 |
| 60 is half 40 |
| What is known about the angles labelled 70, 40, p |
| 70 is the same as 40 |
| 70 and 40 add to twice p |
| Nothing, 70, 40, and p are not related by any geometry rule |
| 70 and 40 add to p |
| 70, 40, and p add up to 180° |
| p and 40 add to 70 |
| What is known about the angles labelled 30, 30, z |
| 30 is the same as 30 |
| 30, 30, and z add up to 180° |
| z and 30 add to 30 |
| 30, 30, and z add up to 360° |
| 30 is half 30 |
| 30 and 30 add to z |
| What is known about the angles labelled 30, 70, r |
| 30 and 70 add to r |
| 30, 70, and r add up to 90° |
| 30, 70, and r add up to 180° |
| 30 and 70 add to twice r |
| 30, 70, and r add up to 360° |
| r and 70 add to 30 |