Angle — 55° (Acute Angle) — free printable diagram

What is a 55 degree angle?

A 55 degree angle (55°) is an acute angle — it measures less than 90°, so the opening is narrower than a square corner. This diagram shows 55° opened between two arms meeting at a vertex.

Measure

55°

Type of angle

Acute angle

Complement (adds to 90°)

35°

Supplement (adds to 180°)

125°

Reflex angle on the other side

305°

In radians

11π/36 (≈0.960)

Fraction of a full turn

11/72 of a turn

• A 55° 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° − 55° = 125°.
• Two angles that add up to 90° are complementary, so the complement of 55° is 90° − 55° = 35°.
• Angles round a point add up to 360°, so the reflex angle on the other side of these arms measures 360° − 55° = 305°.
• 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 55°.
• In radians, 55° × π/180 = 11π/36, which is about 0.960.