IB AA · Unit 2 · 18A Radian Measure
Write a fraction. Put 180° over π radians so the radians cancel. Multiply straight across, then reduce.
The conversion
1 full turn is 2π radians and also 360°. That gives the factor
180°π radians
Always put radians on the bottom so they cancel. The π cancels too. Multiply straight across, then reduce.
No π in the given angle
If the given angle is a decimal number of radians, π stays in the denominator.
Use a calculator. Round to 1 decimal place.
The π cancels. The answer is a whole number of degrees.
2π 3×180°π
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
360°3 = 120°
Answer: 120°
π radians6×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
180°6 = 30°
Answer: 30°
3π radians4×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
540°4 = 135°
Answer: 135°
5π radians3×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
900°3 = 300°
Answer: 300°
3π radians2×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
540°2 = 270°
Answer: 270°
5π radians4×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
900°4 = 225°
Answer: 225°
More than one full turn is fine. Keep the sign.
7π 5×180°π
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
1260°5 = 252°
Answer: 252°
5π radians12×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
900°12 = 75°
Answer: 75°
11π radians4×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
1980°4 = 495°
Answer: 495°
−2π radians3×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
−360°3 = −120°
Answer: −120°
8π radians5×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
1440°5 = 288°
Answer: 288°
13π radians6×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
The π factors cancel too.
Multiply straight across, then reduce.
2340°6 = 390°
Answer: 390°
There is no π on top. Use a calculator and round to 1 decimal place.
0.75 1×180°π
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
135°π ≈ 43.0°
Answer: 43.0°
0.4 radians1×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
72°π ≈ 22.9°
Answer: 22.9°
1.15 radians1×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
207°π ≈ 65.9°
Answer: 65.9°
2.08 radians1×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
374.4°π ≈ 119.2°
Answer: 119.2°
−1.2 radians1×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
−216°π ≈ −68.8°
Answer: −68.8°
5.5 radians1×180°π radians
Radians go on the bottom of the conversion so the radians cancel.
There is no π on top to cancel, so π stays in the denominator.
Use a calculator. Round to 1 decimal place.
990°π ≈ 315.1°
Answer: 315.1°
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