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.
morePractice:
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 30, 50, r
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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 60, 30, y |
| 60 is half 30 |
| 60, 30, and y add up to 360° |
| y and 30 add to 60 |
| 60, 30, and y add up to 180° |
| 60 and 30 add to twice y |
| 60 is the same as 30 |
| What is known about the angles labelled 55, 75, b |
| 55, 75, and b add up to 90° |
| 55, 75, and b add up to 180° |
| 55 is the same as 75 |
| b and 75 add to 55 |
| 55 is half 75 |
| 55 and 75 add to twice b |
| What is known about the angles labelled 40, 70, b |
| 40, 70, and b add up to 360° |
| 40, 70, and b add up to 90° |
| 40, 70, and b add up to 180° |
| 40 is half 70 |
| 40 is the same as 70 |
| Nothing, 40, 70, and b are not related by any geometry rule |
| What is known about the angles labelled 75, 48, c |
| 75, 48, and c add up to 360° |
| Nothing, 75, 48, and c are not related by any geometry rule |
| 75, 48, and c add up to 90° |
| 75 and 48 add to twice c |
| 75, 48, and c add up to 180° |
| 75 and 48 add to c |
| What is known about the angles labelled 70, 60, r |
| 70, 60, and r add up to 180° |
| 70, 60, and r add up to 90° |
| 70 is half 60 |
| 70, 60, and r add up to 360° |
| 70 and 60 add to twice r |
| 70 and 60 add to r |
| What is known about the angles labelled 75, 40, p |
| 75 is the same as 40 |
| 75, 40, and p add up to 180° |
| 75, 40, and p add up to 90° |
| 75, 40, and p add up to 360° |
| Nothing, 75, 40, and p are not related by any geometry rule |
| p and 40 add to 75 |
| What is known about the angles labelled 40, 60, c |
| 40 and 60 add to c |
| Nothing, 40, 60, and c are not related by any geometry rule |
| 40, 60, and c add up to 180° |
| 40, 60, and c add up to 360° |
| 40 and 60 add to twice c |
| 40 is the same as 60 |