4th Grade Measuring and Drawing Angles Worksheet Solutions (PDF)

A full circle is split into 360 one-degree slices.

360°

A half turn is half of a full turn: \(360 \div 2 = 180\).

180°

\(360 \div 4 = 90\). A quarter turn makes a right angle.

90°

One quarter is 90°, so three quarters is \(3 \times 90 = 270\).

270°

One ray is on 0. The other ray crosses the scale at 50. It is less than 90, so it is acute.

50°

The second ray crosses the scale at 130. It is greater than 90, so it is obtuse.

130°

1. \(35^{\circ}\) is less than 90: acute.
2. \(90^{\circ}\) is exactly 90: right.
3. \(120^{\circ}\) is more than 90: obtuse.
4. \(72^{\circ}\) is less than 90: acute.

acute, right, obtuse, acute

Subtract the two readings: \(80 – 30 = 50\).

50°

Draw a ray. Put the protractor center on its endpoint and mark 45 on the scale. Draw a second ray through the mark.

A 45° angle (acute)

Draw a ray, line up the protractor, and mark 120 on the scale. Join the mark to the vertex.

A 120° angle (obtuse)

\(40 + 25 = 65\).

65°

\(90 – 38 = 52\). Check: \(38 + 52 = 90\).

52°

\(180 – 115 = 65\). Check: \(115 + 65 = 180\).

65°

\(30 + 45 = 75\), then \(75 + 25 = 100\).

100° (obtuse)

From 12 to 4 is 4 numbers: \(4 \times 30 = 120\).

120°

\(3 \times 45 = 135\).

135°

\(70 + 35 = 105\). Since 105 is greater than 90, the angle is obtuse.

105°, obtuse

A quarter turn is 90°. Then \(90 + 45 = 135\).

A half turn is 180°: \(180 – 135 = 45\).

135°; 45° more

First unknown: \(90 – 37 = 53\).

Second unknown: \(53 – 20 = 33\).

53° and 33°

Full circle: 360°. B must sweep \(360 – 210 = 150\).

If B sweeps 90°, the dry part is \(150 – 90 = 60\).

150°; 60° dry