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Trapezoid Calculator

Trapezoid Calculator

Calculate trapezoid area and perimeter with special support for isosceles trapezoids. Get step-by-step solutions for all calculations.

Trapezoid Calculator

Calculate area, perimeter, and special trapezoid properties

Real-World Applications

Stadium Seating

Trapezoidal sections provide optimal viewing angles

Upper: 20m, Lower: 30m, Height: 15m → Area: 375m²

Dam Cross-Section

Wider base provides stability against water pressure

Top: 5m, Bottom: 15m, Height: 20m → Area: 200m²

Bucket Shape

Tapered design for easy manufacturing and stacking

Top: 25cm, Bottom: 20cm, Height: 30cm → Area: 675cm²

Trapezoid Types & Common Mistakes

📐 Trapezoid Types:

  • • General: One pair of parallel sides
  • • Isosceles: Equal legs, symmetric
  • • Right: One or more right angles
  • • Scalene: All sides different lengths

❌ Common Mistakes:

  • • Forgetting to divide by 2 in area formula
  • • Using wrong bases (not parallel sides)
  • • Confusing leg length with height
  • • Not checking if trapezoid is isosceles

Trapezoid Formulas

Area Formula

Average of parallel sides times height

A=12(b1+b2)×hA = \frac{1}{2}(b_1 + b_2) \times h

Perimeter

Sum of all four sides

P=b1+b2+s1+s2P = b_1 + b_2 + s_1 + s_2

Isosceles Trapezoid

Equal non-parallel sides

s1=s2=ss_1 = s_2 = s

Common Mistake Warning!

Don't forget to divide by 2 in the trapezoid area formula!

❌ Wrong:

A=(b1+b2)×hA = (b_1 + b_2) \times h

✓ Correct:

A=12(b1+b2)×hA = \frac{1}{2}(b_1 + b_2) \times h

Types of Trapezoids

General Trapezoid

One pair of parallel sides, non-parallel sides may be different lengths

P=b1+b2+s1+s2P = b_1 + b_2 + s_1 + s_2

Isosceles Trapezoid

Non-parallel sides are equal, base angles are equal

P=b1+b2+2sP = b_1 + b_2 + 2s

Related Tools & Learning

Trapezoid Lesson

Learn trapezoid properties and formulas

Parallelogram Calculator

Calculate parallelogram properties

Rectangle Calculator

Calculate rectangle area and perimeter

Frequently Asked Questions

The area of a trapezoid is A = ½(b₁ + b₂) × h, where b₁ and b₂ are the parallel bases and h is the perpendicular height. Don't forget to divide by 2!
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