Question

Determine the value of x. Round your answer to the nearest whole number, if necessary.

Answer 1

By definition:

cos(angle) = adjacent/hypotenuse

In triangle ABD:

cos(∠A) = 10/x

In triangle ABC:

cos(∠A) = x/40

Then,

`\begin{gathered} (10)/(x)=(x)/(40) \\ 10\cdot40=x\cdot x \\ 400=x^2 \\ \sqrt[]{400}=x \\ 20=x \end{gathered}`