The bases of a triangle and a parallelogram are equal in area. The height of the parallelogram is 10 cm, what is the height of the triangle.
一个三角形和一个平行四边形底相等面积也相等．平行四边形的高是10cm，三角形的高是多少．
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>