Grade 6 · Math · Unit 9 of 12
Angles & Triangles
Measure, classify, find missing angles
What your child practises
Estimating and classifying angles (acute, right, obtuse, straight, reflex), finding missing angles on a line and in triangles, and classifying triangles by their sides and angles.
BC Curriculum learning standard: Angle measurement and classification; triangles
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
A triangle has sides of 10 cm, 10 cm and 11 cm. What type of triangle is it?
- scalene
- isosceles
- equilateral
Show answer
isosceles
Hint: Classify by sides. Equilateral: all 3 sides equal. Isosceles: 2 sides equal. Scalene: no sides equal.
Question 2
Two angles together make a straight line. One of them is 42°. What is the other angle?
answer box°
Show answer
138 °
Hint: Angles that make a straight line add to 180°. Subtract the angle you know from 180°.
Question 3
This angle measures 180°. What kind of angle is it?
- right
- acute
- straight
- reflex
- obtuse
Show answer
straight
Hint: Acute: less than 90°. Right: exactly 90°. Obtuse: between 90° and 180°. Straight: exactly 180°. Reflex: more than 180°.
Question 4
Two angles of a triangle are 94° and 48°. What is the third angle?
answer box°
Show answer
38 °
Hint: The three angles in any triangle add to 180°. Add the two you know, then subtract from 180°.
Question 5
Can a triangle have two right angles?
- No, two right angles already add to 180°
- Yes, but only if it is isosceles
- Yes, if the third side is long enough
- Only if it is equilateral
Show answer
No, two right angles already add to 180°
Hint: The three angles of a triangle add to exactly 180°. Two 90° angles would leave 0° for the third.
Question 6
About how many degrees is this angle?
- 105°
- 45°
- 150°
- 285°
Show answer
150°
Hint: Compare with benchmarks: a square corner is 90°, a straight line is 180°, and three quarters of a full turn is 270°.