Angle — 20° (Acute Angle) — free printable diagram

What is a 20 degree angle?

A 20 degree angle (20°) is an acute angle — it measures less than 90°, so the opening is narrower than a square corner. This diagram shows 20° opened between two arms meeting at a vertex.

Measure

20°

Type of angle

Acute angle

Complement (adds to 90°)

70°

Supplement (adds to 180°)

160°

Reflex angle on the other side

340°

In radians

π/9 (≈0.349)

Fraction of a full turn

1/18 of a turn

• A 20° angle is an acute angle because it measures less than 90°, so the opening is narrower than a square corner.
• Angles on a straight line add up to 180°, so the angle next to this one measures 180° − 20° = 160°.
• Two angles that add up to 90° are complementary, so the complement of 20° is 90° − 20° = 70°.
• Angles round a point add up to 360°, so the reflex angle on the other side of these arms measures 360° − 20° = 340°.
• To measure or draw it, put the centre of the protractor on the vertex where the two arms meet, line one arm up with the 0° mark, and read the scale that starts at 0° on that arm until you reach 20°.
• In radians, 20° × π/180 = π/9, which is about 0.349.