Example 1easy
- A)75°
- B)85°
- C)90°
- D)100°
Step-by-step solution
- The sum of angles around a point is 360°.
- Add the given angles: 75° + 110° + 90° = 275°.
- Subtract this sum from 360° to find the fourth angle: 360° - 275° = 85°.
Answer: 85°
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Explore complementary, supplementary, and vertically opposite angles with parallel lines. This topic is part of the IB Class 7 mathematics syllabus (chapter: Unit 5). On this page you can practice 60 questions across three difficulty levels — 20 easy, 20 medium, and 20 hard — each with a visual step-by-step solution, plus a timed 35-question mastery test with a live leaderboard. Worked examples and sample questions from the topic are below.
Interactive lesson · about 15 minutes · checkpoint question after every unit
Step-by-step solution
Answer: 85°
Step-by-step solution
Answer: D. 135°
Step-by-step solution
Answer: B. 119°
Q1.easy
Answer: 48°
Hint: Angles on a straight line always add up to a specific total. Think about a protractor.
Q2.easy
Answer: 65°
Hint: Vertically opposite angles have a special relationship regarding their measures.
Q3.easy
Answer: 110°
Hint: Think about the position of corresponding angles relative to the parallel lines and transversal.
Q4.medium
Answer: A. 30
Hint: Angles on a straight line are supplementary, meaning they add up to 180°.
Q5.medium
Answer: A. 75°
Hint: First, find the adjacent angle on the straight line. Then, consider its vertically opposite angle.
Q6.medium
Answer: A. 130°
Hint: Identify the relationship between the two angles described: they are corresponding angles.
Q7.hard
Answer: A. 40
Hint: Recall that angles on a straight line sum to 180°. Form an equation with the given algebraic expressions.
Q8.hard
Answer: C. If ∠AEC = 70°, then ∠CEB = 110°.
Hint: Recall the definitions of vertically opposite angles and angles on a straight line. Consider how these relationships apply to intersecting lines.
Q9.hard
Answer: D. 40
Hint: For lines to be parallel, corresponding angles must be equal. Identify the corresponding angles in the given description.
These are 9 of the 60 questions available for Angle Relationships. Start practicing above to unlock visual solutions, AI coaching, and the topic leaderboard — completely free.