Trapezoid Angle Calculator: Find All Four Interior Angles

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Choose whether to enter a known angle or the side lengths and height.
Isosceles trapezoids have equal legs and matching base angles. Right trapezoids have one leg perpendicular to both bases.
The acute or obtuse base angle on the left leg. Must be between 1 and 179 degrees.
deg
Angle alpha (bottom-left)Isosceles trapezoid
65deg

Interior angle at the bottom-left vertex

Angle beta (top-left)115deg
Angle delta (bottom-right)65deg
Angle gamma (top-right)115deg
Sum of all angles360deg
Alpha (bottom-left)65
Beta (top-left)115
Delta (bottom-right)65
Gamma (top-right)115

All four trapezoid angles solved. Sum = 360 deg.

  • The four angles are: alpha = 65.00 deg, beta = 115.00 deg, delta = 65.00 deg, gamma = 115.00 deg.
  • Angles alpha and beta are supplementary (they share the same left leg) and sum to exactly 180 deg.
  • Angles delta and gamma are supplementary (they share the same right leg) and sum to exactly 180 deg.
  • Because alpha equals delta, this is an isosceles trapezoid: both legs are equal in length and the shape is symmetric about its median.

Next stepTo find the area of the trapezoid, multiply the sum of the two bases by the height and divide by two: A = (a + b) x h / 2.

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