CK-12 Foundation
Ck 12: Trigonometry: Reference Angles and Angles in the Unit Circle
[Free Registration/Login may be required to access all resource tools.] Definition of reference angle shown on the unit circle.
CK-12 Foundation
Ck 12: Trigonometry: Rotations in Radians
[Free Registration/Login may be required to access all resource tools.] Express rotations in radian measure
Lawrence Hall of Science
The Math Page: Trigonometry: Radian Measure
Here is a site that clearly and thoroughly explains the radian measure of angles. There are example problems solved, problems for the student to attempt, and answers to the student problems.
Math Is Fun
Math Is Fun: Unit Circle
Students learn about the unit circle. Topics include degrees, radians, and Pythagoras' Theorem. The tutorial consists of notes and examples.
Savvas Learning
Pearson Education: Radian and Degree Angle Measures [Pdf]
This resource details how to convert between radians and degrees with worked examples. It also looks at special radian measures that are used often.
Khan Academy
Khan Academy: Radians and Degrees
Convert angle measures given in degrees to radians and vice versa. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Lawrence Hall of Science
The Math Page: Trigonometry: Arc Length
Here is a site that clearly and thoroughly explains arc length and its relationship to radian measure of angles. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point this site...
Lawrence Hall of Science
The Math Page: Trigonometry: Measurement of Angles
Here is a site that clearly and thoroughly explains many topics regarding measurement of angles, including standard position, degree measure, and coterminal angles. There are example problems solved, problems for the student to attempt,...
Lawrence Hall of Science
The Math Page: Trigonometry
Concepts in Trigonometry are explained and illustrated here by a member of the math department at Borough of Manhattan Community College.
Illustrative Mathematics
Illustrative Mathematics: F Tf.1 What Exactly Is a Radian?
For this task, students use a piece of string or another tool to measure the radius of the circle and then mark off the corresponding arc length on the unit circle as many times as they need to for 0, 1, 2, 3, 4, 5, and 6 radians. They...
Illustrative Mathematics
Illustrative Mathematics: F Tf Bicycle Wheel
The purpose of this task is to introduce radian measure for angles in a situation where it arises naturally, in this case the movement of a bicycle wheel. Aligns with HSF-TF.A.1.
Khan Academy
Khan Academy: Algebra Ii: Trig Values of Special Angles
Find the sine and cosine of special angles, which are angles whose trig values we can determine without the use of a calculator. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or...
Purple Math
Purplemath: Converting Between Radians and Degrees
Describes degrees and radians with respect to angles, the reason for the invention and use of radians, and how to convert between radians and degrees.
Exploratorium
Exploratorium: Ilion High: Build a Clinometer
Instructions for building a clinometer are given on this page. Clinometers can be used to measure the angle of elevation of a right triangle, and in turn find the height of large objects.
Mathigon
Mathigon: Geometry: Circle and Pi: Degrees and Radians
Rather than dividing a circle into some number of segments (like 360 degrees), mathematicians often prefer to measure angles using the circumference of a unit circle - a circle with radius 1. This way of measuring angles is called...
Other
Gobierno De Navarra: Medidas De Angulos
Interactive figures to learn about the sum of the measurement of the angles of different plane figures.
National Council of Teachers of Mathematics
Nctm: Illuminations: Pi Fight
Become comfortable with using both radians and degrees.
Khan Academy
Khan Academy: Solve for an Angle in Right Triangles
Given two sides in a right triangle, find one of the acute angles using trigonometry.
Khan Academy
Khan Academy: Radians & Degrees
Convert angle measures given in degrees to radians and vice versa.
CK-12 Foundation
Ck 12: Algebra Ii: 4.4 Radians
This section introduces radians an alternative to degrees as a way to measure the rotation around a circle. It also begins to draw connections between radians and trigonometric identities.
CK-12 Foundation
Ck 12: Algebra Ii: 4.3 the Unit Circle
Activities in this lesson explore how to identify the coordinates where special right triangles intersect with the unit circle in all four quadrants, use both degrees and radians to identify angles, and explore angles of different sizes...
Khan Academy
Khan: Lesson 16: Part 2 Coordinate Geometry; Trigo and Radians; Complex Numbers
2 OF 2 FOR ADDITIONAL TOPICS IN MATH. Students will use the coordinate plane and equations of lines and circles to describe figures; create the equation of a circle given the figure or use the structure of a given equation to determine a...
Khan Academy
Khan Academy: Radians & Arc Length
Solve problems related to radians and arc length like finding an arc length given the central angle and radius.