Question

Which equation can be solved to find one of the missing side lengths in the triangle?

Answer 1

Answer:

$cos(60^o)=\frac{a}{12}$

Step-by-step explanation:

The complete question in the attached figure

we know that

In the right triangle of the figure

The cosine of the angle of 60 degrees is equal to divide the adjacent side to the angle of 60 degrees (BC) by the hypotenuse (AB)

so

$cos(60^o)=\frac{BC}{AB}$

we have

$BC=a\ units\\AB=12\ units$

substitute the values

$cos(60^o)=\frac{a}{12}$