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Cosine

Definition Of Cosine

In a right-angles triangle Cosine is the ratio of length of the adjacent side to the length of the hypotenuse.

More About Cosine

Cosine is also written as cos.

Example of Cosine

EXAMPLE OF Cosine

cos θ = EXAMPLE OF Cosine & cos θ = 4/5

Video Examples: Sine and Cosine Rule 1 (GCSE Higher Maths)

Solved Example on Cosine

Ques: If x = 8 units, y = 15 units, and a = 17 units, then find the value of cos C in the right triangle ABC.

example of  Cosine

Choices:

A. 15/17
B. 17/18
C. 17/15
D. 8/17
Correct Answer: D

Solution:

Step 1: Cos C = example of  Cosine
Step 2: In â–³ABC, the adjacent side of C is example of  Cosine and the hypotenuse isexample of  Cosine .
Step 3: So, Cos C = example of  Cosine
Step 4: = 8/17 [Substitute BC = 8 and AC = 17.]