Use the formula for area: (A = frac{1}{2}bh)
Rearrange to find height: (h = frac{2A}{b})
Measure or find the triangle’s area (A)
Measure or find the base length (b)
Substitute the values into (h = frac{2A}{b})
Calculate the result
If the triangle is right-angled, use the perpendicular side as the height
If the triangle is isosceles, split it into two right triangles and use Pythagoras if needed
If only side lengths are known, use Heron’s formula to find the area first, then calculate the height