Question

In AJKL, j = 74 cm, k = 14 cm and l=80 cm. Find the measure of ZJ to the nearestdegree.

Answer 1

To answer this question we first draw the triangle to help us:

As a note on the problem: This is not necessarily the triangle we have, we drew just to helps us solve it.

Now, to find the angle J we can use the law of cosines:

`j^2=k^2+l^2-2kl\cos J`

Plugging the values we have and solving for J we have:

`\begin{gathered} 74^2=14^2+80^2-2(14)(80)\cos J \\ 2(14)(80)\cos J=14^2+80^2-74^2 \\ \cos J=(14^2+80^2-74^2)/(2(14)(80)) \\ J=\cos ^(-1)((14^2+80^2-74^2)/(2(14)(80))) \\ J=60 \end{gathered}`

Therefore the angle J is 60°.