Duration of the online course: 6 hours and 35 minutes
4.62
(39)
Build confidence with trigonometry in this free online course: master sine, cosine, radians, unit circle, graphs and real-world problems—learn fast, practice more.
In this free course, learn about
Meaning of “trig” and core right-triangle trig ratios (SOH-CAH-TOA)
Compute trig values in special triangles (30-60-90, 45-45-90) and unit circle
Convert degrees↔radians; interpret π, τ, and angle measure on the unit circle
Use trig functions to solve for unknown sides/angles in right-triangle problems
Extend trig definitions via the unit circle; key values like sin(π), cos(−θ), etc.
Graph sin, cos, tan; identify amplitude, period, phase/vertical shifts from equations
Determine an equation/model of a trig function from a graph or key features
Apply and prove trig identities: Pythagorean, sum formulas, double-angle, etc.
Solve word problems using trig, including navigation, ferris wheel height, distances
Use Law of Sines and Law of Cosines (and their proofs) for non-right triangles
Work with polar coordinates: convert to/from Cartesian; rewrite polar curves
Evaluate inverse trig (arcsin, arccos, arctan) with principal values and angles
Tackle advanced trig problems: maxima/minima, constraints, systems, geometry areas
Course Description
Strengthen your math foundation and unlock the ideas behind angles, triangles, and circular motion with this free online trigonometry course. Designed for students and independent learners, it helps you move from memorizing formulas to truly understanding what trigonometric functions represent and how to use them to solve problems.
You will start by connecting right-triangle relationships to the meaning of sine, cosine, and tangent, then expand that intuition to the unit circle, where trigonometry becomes a powerful language for any angle. You will get comfortable switching between degrees and radians, interpreting common angles, and reasoning about values rather than guessing. As your understanding grows, you will see how trigonometric functions behave on graphs, how period and amplitude change, and how these patterns connect back to geometry and circles.
Along the way, guided practice reinforces each skill with targeted exercises that train accuracy and speed. You will learn to choose the right function for a situation, work confidently with inverse trig, and translate between coordinate systems using polar and Cartesian representations. The course also builds fluency with identities, including why they are true and how they simplify expressions and unlock cleaner solutions.
Finally, you will apply trigonometry to realistic scenarios such as navigation, distances, and cyclic motion, gaining the kind of problem-solving ability used in school exams and beyond. By the end, you should feel prepared to tackle homework, standardized tests, and more advanced topics like precalculus and physics with a clearer, more dependable trigonometry toolkit.
