Practice Radians in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A radian is an angle measurement defined by the arc length it subtends on a unit circle: one radian is the angle at which the arc length equals the radius. A full circle is 2π radians (about 6.28 radians), making radians the natural unit for trigonometry and calculus.

It ties angle directly to the circle’s geometry instead of degree counting.

Showing a random 20 of 50 problems.

Example 1

medium
Convert 3π4 radians to degrees.

Example 2

challenge
Show that for small θ in radians, sin⁡θ≈θ. Use it to estimate sin⁡(0.05).

Example 3

hard
Find the area of a sector with radius 12 cm and arc length 9 cm.

Example 4

easy
Convert 270∘ to radians.

Example 5

medium
A central angle of π2 radians subtends an arc of length 5 cm. What is the radius?

Example 6

easy
Convert π3 radians to degrees.

Example 7

easy
In a unit circle, what arc length is subtended by an angle of π/4 radians?

Example 8

easy
Approximately how many degrees is 1 radian?

Example 9

challenge
On a circle of radius r, an inscribed angle subtends an arc of length πr/3. Find the inscribed angle in radians.

Example 10

medium
A pendulum swings through an arc of 0.8 m on a string of length 2 m. Find the angle swept in radians.

Example 11

hard
Compute the linear speed at the equator due to Earth's rotation if Earth's radius is 6378 km and it rotates once every 24 hours.

Example 12

hard
Find tan⁡(5π6).

Example 13

easy
Convert 360° to radians.

Example 14

medium
Convert 7π4 radians to degrees and identify which quadrant this angle is in.

Example 15

medium
Find the area of a sector with radius 4 and central angle π2.

Example 16

hard
A wheel of radius 30 cm rotates at 120 rpm (revolutions per minute). Find the angular velocity in radians per second and the linear speed of a point on the rim.

Example 17

medium
Express −π3 as a positive coterminal angle in [0,2π).

Example 18

easy
Convert π radians to degrees.

Example 19

easy
Convert 60∘ to radians.

Example 20

medium
A wheel turns through 4π radians. How many full revolutions is that?