Correct response:
- The height of equilateral triangle ΔABC is <u>12 inches</u>
<h3>Methods used to calculate the height of ΔABC</h3>
Given:
ΔABC is a equilateral triangle
Point <em>D</em> is on side BC
Point <em>R</em> is on side AB
Point <em>T</em> is on side AC
DR = 4 inches
DT = 8 inches
Required:
The height in inches of equilateral triangle ΔABC.
Solution:
By sine rule, we have;

Therefore;
4·sin(60° - θ) = 8·sin(θ)
- sin(A - B) = sin(A)·cos(B) - cos(A)·sin(B)
Therefore;
4·(sin(60°)·cosθ - cos(60°)·sin(θ)) = 8·sin(θ)
Dividing by sin(θ) gives;
4·(sin(60°)·cot(θ) - cos(60°)) = 8
sin(60°)·cot(θ) - cos(60°) = 8 ÷ 4 = 2
Multiplying by 2 gives;
√3·cot(θ) - 1 = 4
√3·cot(θ) = 4 + 1 = 5

Therefore;


Length of a side of the equilateral triangle,<em> L</em>, is therefore;

Therefore;

Height, <em>h</em>, of the equilateral triangle ΔABC is, h = L × sin(60°)
Therefore;

- The height of the equilateral triangle, h = <u>12 inches</u>
Learn more about trigonometric ratios here:
brainly.com/question/16829589