Remmeber that
An equilateral triangle has three equal sides and three equal interior angles
the measure of each interior angle is 60 degrees
that means
the measure of angle B is 60 degrees
Find the value of x
In the right triangle CAD
we have
sin(60)=x/8 ------> by opposite side divided by the hypotenuse
solve for x
x=8*sin(60)
Remember that
therefore