Works for all trapezoids?

Yes, as long as you know both parallel sides and the height.

Trapezoid Area Calculator

Calculate area of a trapezoid

Base a (top)

Base b (bottom)

Height

A = (a + b)/2 × h

Average of parallel sides times the height.

Area = 32.

Calculate the area of a trapezoid.

Calculate percentages, increases, and decreases

Add, subtract, multiply, and divide fractions

Calculate mean, median, and mode of numbers

Find standard deviation of a data set