standard_description: Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side.
problem_activity: Task
Below are pictures of four quadrilaterals: a square, a rectangle, a trapezoid and a parallelogram.
[IMG]
For each quadrilateral, find and draw all lines of symmetry.


aligns: no