Question

Find the length of BC. Round your answer to two decimal places.

Answer 1

`\\ \rm\Rrightarrow cos40=(Base)/(Hypotenuse)`

`\\ \rm\Rrightarrow cos40=(a)/(10)`

`\\ \rm\Rrightarrow 0.766=a/10`

`\\ \rm\Rrightarrow a=0.766(10)`

`\\ \rm\Rrightarrow a=76.6`

Answer 2

7.66 (dp)

Explanation:

Use the cosine trig ratio:

`\mathsf{\cos(\theta)=(A)/(H)}`

where:

• 
  `\theta` is the angle
• A is the side adjacent the angle
• H is the hypotenuse

Given:

• 
  `\theta` = 40°
• A = a
• H = 10 in

Substituting the given values into the equation:

`\implies \mathsf{\cos(40)=(a)/(10)}`

`\implies \mathsf{a=10\cos(40)}`

`\implies \mathsf{a=7.660444431...}`

`\implies \mathsf{a=7.66 \ (2 \ dp)}`