Lesson 2. Angles

Acute, obtuse, reflex and right angles.

An acute angle is less that a ¹/₄ turn (90⁰)

A right angle is a ¹/₄ turn (90⁰)

An obtuse angle is more that a ¹/₄ turn (90⁰) and less that a ¹/₂ turn (180⁰)

A reflex angle is more that a ¹/₂ turn (180⁰)

Labels for angles.

This is called angle BCD or angle DCB. We write this as

Angles on a straight line and angles at a point.

EXAMPLE:

The angles on a straight line add up to 180⁰.

EXAMPLE:

The angles at a point add up to 360⁰.

Vertically opposite angles and angles in a triangle.

EXAMPLE:

When 2 lines intersect the opposite angles are equal. Ie, vertically opposite angles are equal.

x = 42⁰ 

Test lesson 2

• Test 1
• Test 2
• Test 3