Don't just memorize — understand! See why the area formulas make sense.
Why do we multiply? Let's count the squares!
When you have a rectangle, you're arranging unit squares (1×1 squares) in rows and columns.
Length tells you how many squares fit across (columns).
Width tells you how many rows you have.
So length × width = total number of squares = area!
A triangle is exactly HALF of a rectangle!
Imagine a rectangle with the same base and height as your triangle.
If you draw a diagonal line, you split the rectangle into two identical triangles.
So: Triangle area = ½ of rectangle area
Rectangle area = base × height
Triangle area = ½ × base × height
10 cm × 6 cm = 60
½ × 10 cm × 6 cm = 30
It's a "pushed" rectangle — same area!
If you cut a triangle from one side of a parallelogram and move it to the other side, you get a rectangle!
The rectangle has the same base and height as the parallelogram.
So they have the same area: base × height
The slanted side is NOT the height. Always use the perpendicular distance (the dotted line with the right-angle square □).
Average the two bases, then treat it like a rectangle!
A trapezoid has two different bases — one short (b₁) and one long (b₂).
Step 1: Find the average width: (b₁ + b₂) ÷ 2
Step 2: Multiply by height, just like a rectangle!
Formula: ½ × (b₁ + b₂) × h