Question

Determine which of the two acute angles has a cosine ofB 6 A8COS1011//CT/P

Answer 1

Given:

The right traingle ABC with side measurements.

Required:

`\text{ Determine which of two acute angle has cosine of }(4)/(5).`

Step-by-step explanation:

First draw a figure

We need here cosine law

`cosC=(a^2+b^2-c^2)/(2ab)`

So, we have a = 8, b = 10 and c = 6.

So, cosine of acute angle C

`\begin{gathered} cosC=(a^2+b^2-c^2)/(2ab) \\ cosC=(8^2+10^2-6^2)/(2*8*10) \\ cosC=(64+100-36)/(160) \\ cosC=(128)/(160) \\ cosC=(4)/(5) \end{gathered}`

Answer:

`\text{ Acute angle }C\text{ has cosine }(4)/(5).`