
The inradius formula provided is:
\[ r = \frac{P + B - H}{2} \] Where: - \( P \) represents the perimeter, - \( B \) represents the base, and - \( H \) represents the height of the triangle.
Substitute the given values into the formula: \[ 4 = \frac{P + 10 - H}{2} \] Multiply both sides by 2: \[ P + 10 - H = 8 \] Rearrange the equation: \[ P - H = -2 \] Therefore: \[ H = P + 2 \]
Apply the Pythagorean Theorem: \[ P^2 - 10^2 = H^2 \] Substitute \( H = P + 2 \) into the equation: \[ P^2 - 100 = (P + 2)^2 \] Expand the equation: \[ P^2 - 100 = P^2 + 4 + 4P \] Simplify the equation: \[ 4P = 96 \] Solve for \( P \): \[ P = 24 \]
The area \( A \) of the triangle is calculated as: \[ A = \frac{1}{2} \times B \times H \] Substitute the known values: \[ A = \frac{1}{2} \times 10 \times 24 = 120 \]
The area of the triangle is \( \boxed{120} \) square inches.