BetaCalculus Corner is in beta: things may change while we test, and payments aren't open yet.

© Calculus CornerGetting started Terms Privacy Contact

Chapter 03Trigonometry

0103.01Triangle Basics
0203.02Types of Triangles
0303.03Similar and Congruent Triangles
0403.04Pythagorean Theorem and Special Triangles
0503.05Sine, Cosine, and Tangent
0603.06The Unit Circle
0703.07Secant, Cosecant, and Cotangent
0803.08Trigonometric Identities
0903.09Solving Trigonometric Equations
1003.10Inverse Trigonometric Functions
1103.11The Law of Sines
1203.12The Law of Cosines

Chapter 03 · Trigonometry

0103.01Triangle Basics
0203.02Types of Triangles
0303.03Similar and Congruent Triangles
0403.04Pythagorean Theorem and Special Triangles
0503.05Sine, Cosine, and Tangent
0603.06The Unit Circle
0703.07Secant, Cosecant, and Cotangent
0803.08Trigonometric Identities
0903.09Solving Trigonometric Equations
1003.10Inverse Trigonometric Functions
1103.11The Law of Sines
1203.12The Law of Cosines

Topics / 03 Trigonometry

03.12

The Law of Cosines

The Pythagorean theorem for any triangle: find a side from two sides and the angle between them, or an angle from three sides.

About 15 minutes

You'll learn to

→Use the Law of Cosines with SAS and SSS
→Find an angle from three sides
→Choose between the Law of Sines and the Law of Cosines

← 03.11 The Law of Sines 04.01 Determining Limits Graphically →

Semester Pass

Unlock this lesson and every other topic

The full explanation, videos and 6 practice problems for this lesson are part of the Semester Pass: $49 once for 4 months of full access. No subscription, nothing renews.

Create a free account What's included

The first section of every chapter is free. Try 03.01 Triangle Basics.