Law of Cosines Practice Problems
Probelm 1: If two sides of the triangle are 20 cm and 22 cm and the angle between them is 45° then find the third side of the triangle.
Probelm 2: If two sides of the triangle are 3 cm, 4 cm, and 5 cm then find the angle ‘A’ of the triangle.
Probelm 3: If two sides of the triangle are 8 cm and 12 cm and the angle between them is 60° then find the third side of the triangle.
Probelm 4: If two sides of the triangle are 12 cm, 18 cm, and 16 cm then find the angle ‘A’ of the triangle.
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
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