A trapezoid looks like a rectangle with 2 traingles attached to the side, yeah? So imagine cutting off those 2 triangles. In the middle you have a rectangle with the dimensions of 14 cm by 16 cm. The area of that rectagle is 224 cm². By subtracting the top base length from the bottom base length, you get the length of the two triangles. So, it would be 28 cm - 14 cm, giving you 14 cm. There were 2 triangles, so cut that length in half and you get 7 cm for the base of one traingle. To find the area of 1 traingle, you would do 1/2 multiplied by 7 multiplied by 16. But you have 2 triangles. so the 1/2 step isn't needed because if you put the two triangles together, you get a new rectangle. Thus, when you add the area of this new rectangle, you get 112 cm². Add this to the original rectangle, and your final area is 336 cm².
A triangle has three sides. All the corresponding angles of triangle must be congruent. When the triangle is dilated it is rotated 90 degrees clockwise about its origin. The shape of the triangle will not change due to rotation of dilation.
