Mathematics for IGCSE & O level - Mensuration (Section 10 - No. 29)
What do you need to ensure when finding area of a triangle?
Use any side as the base
Use the perpendicular height to the base
Use the sloping side as the height
Don't worry about units
הֶסבֵּר
The height of a triangle must be perpendicular to the base used to calculate the area.