Law of Cosines
What is Law of Cosine in Trigonometry?
Law of Cosine in Trigonometry is the fundamental law of trigonometry that is used to find the angle of the triangle when all three sides of the triangle are given.
What of Law of Cosine Formula?
Law of Cosine formula is,
- a2 = b2 + c2 – 2bc·cos A
- b2 = c2 + a2 – 2ca·cos B
- c2 = a2 + b2 – 2ab·cos C
What is Law of Cosine class 11?
Law of Cosine class 11 is the fundamental law of mathematics that is used to find the angle of the triangle when all three sides of the triangle are given.
Does Law of Cosines work for All Triangles?
Yes. Law of Cosine work for all triangles and it is used for finding angles of the triangle when all its sides are given.
When to Use Law of Cosines?
Cosine rule or cosine formula is used when all three sides of triangle are given and angle of triangle is found.
How to Find Angles Using Cosine Rule?
If in a triangle where a, b and c are the sides of the triangle and C is the angle included between sides, a and b then angle C is calculated as,
Cos C = (a2 + b2 – c2)/2ab
What is Sine Rule Formula?
As per the sine rule, if a, b, and c are the length of sides of a triangle and A, B, and C are the angles, then,
a/sin A = b/sin B = c/ sin C
How is the Law of Cosines different from the Law of Sines?
Law of Cosines applies to all triangles, involving side lengths and angles, while the Law of Sines applies to triangles with known angles and opposite side lengths.
Law of Cosines
Law of Cosines in Trigonometry is the fundamental law of mathematics used to find the angle of the triangle when all three sides of the triangle are given. This law is also called the Cosine Rule Or the Cosine Formula. If in a triangle the sides are a, b, and c, then law of cosine for angle A is given as:
a2 = b2 + c2 – 2bc cos A
Similarly, all other angles B and C are given. In this article, we will learn about, the Law of Cosines, the Law of Cosines formula, examples, and others in detail.
Table of Content
- What is Law of Cosines?
- Law of Cosines Formula
- Law of Cosines Proof
- How to Find Angle using Law of Cosines
- Sine Formula
- Examples Using Law of Cosines