Question

Pls help, I know the answer but what I wrote in the box isn't correct How do I show the answer?

Answer 1

Answer:

AC=11.38 cm

Step-by-step explanation:

The Law of Cosines

It relates the length of the sides of a triangle with one of its internal angles.

Let a,b, and c be the length of the sides of a given triangle, and x the included angle between sides a and b, then the following relation applies:

$c^2=a^2+b^2-2ab\cos x$

The figure shows two triangles and we are required to calculate the length of the side AC, knowing two sides and the angle between them. Thus, applying the formula:

$AC^2=17^2+13^2-2*17*13*\cos42^\circ$

$AC^2=289+169-442*0.7431$

$AC^2=129.53$

$AC=\sqrt{129.53}$

AC=11.38 cm