Geometry: Angles & Triangles

Explore angle relationships, triangle properties, and geometric reasoning.

7th Grade

Geometry

~45 min

🎮 Interactive Activity: Triangle Angle Calculator

Find the missing angle in a triangle!

Triangle with angles: 50°, 60°, and ?

🎮 Interactive Activity: Angle Relationships

Find complementary and supplementary angles!

Complementary angle of 35°

1. Understanding Angles

Types of Angles

Angles are measured in degrees. Understanding angle relationships helps solve geometric problems.

Angle Relationships:

• Complementary angles: Sum to 90°

• Supplementary angles: Sum to 180°

• Vertical angles: Opposite angles formed by intersecting lines are equal

• Adjacent angles: Share a common side and vertex

Example 1: Find complementary angle of 35°

Complementary angle = 90° - 35° = 55°

Example 2: Find supplementary angle of 120°

Supplementary angle = 180° - 120° = 60°

Angle Types:

• Acute: Less than 90°
• Right: Equal to 90°
• Obtuse: Greater than 90° but less than 180°
• Straight: Equal to 180°

2. Triangle Properties

3. Angle Relationships

4. Triangle Classification

5. Problem-Solving Strategies

6. Real-World Applications

Frequently Asked Questions

Practice Time!

Practice Quiz

Questions

Correct

Score

What is the sum of interior angles in any triangle?

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If two angles of a triangle are 50° and 60°, what is the third angle?

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What is the complementary angle of 35°?

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What is the supplementary angle of 120°?

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A triangle with all sides equal is called:

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Which triangle has exactly one angle of 90°?

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Can a triangle have sides of lengths 2, 3, and 7?

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An isosceles triangle has base angles of 70° each. What is the vertex angle?

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Vertical angles are always:

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If two parallel lines are cut by a transversal, corresponding angles are:

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