Question

Find \cos(\alpha)cos(α)cosine, left parenthesis, alpha, right parenthesis in the triangle. Choose 1 answer: Choose 1 answer: (Choice A) A \dfrac{20}{29} 29 20 ​ start fraction, 20, divided by, 29, end fraction (Choice B) B \dfrac{20}{21} 21 20 ​ start fraction, 20, divided by, 21, end fraction (Choice C) C \dfrac{21}{29} 29 21 ​ start fraction, 21, divided by, 29, end fraction (Choice D) D \dfrac{21}{20} 20 21 ​

Answer 1

Check Explanation

Explanation:

The diagram for this question is missing, but from the setup of the question, it is evident that the triangle to obtain cos α from is a right angled triangle.

It is evident from the options provided that the right angled triangle is one with dimensions of 20, 21 and 29.

These three dimensions perfectly form a Pythagorean triple.

So, the value of cos α now depends on the setup of the triangle.

From trigonometric relations, if α is an angle in the right angled triangle, cos α is given mathematically as

Cos α = (Adj/Hyp)

For this Pythagorean triple,

Hyp = hypotenuse side = 29

Adj = Adjacent side = 20 or 21, depending on the triangle's setup.

If the adjacent is 20,

Cos α = (20/29), option A is correct.

If the adjacent is 21,

Cos α = (21/29), option C is correct.

Hope this Helps!!!