Help? my math teacher sucks!?

Question

he doesnt explain anything to me!

i have this stupid online summer school and nobody will even try helping me. im so confused !:'( and i feel really stupid.

i need to know how to solve it, not just the answers please!

Find the area of the figure below. The units are in decimeters.

http://www.omegamath.com/scripts/geometry/Gtest/image6010.gif

Answer 1

The answer to that is 40. If you need me to explain how, email me at:            

[e-mail]

Answer 2

Imagine that dotted line is on both sides of the parallelogram. Normally what you would do is find the area of both triangles (you know that their base together is 6 cm (13-7=6)) and then find the area of the rectangle left over (7X4) then add them together. Now look at the picture. Imagine you took out that part of the shape that has the dotted line, then stuck it on the other side so that it makes a rectangle. Then that would be super easy right? just straight multiplying length and width. But in order to find the width, you have to know how much you would be adding to the other side (or taking away from the side, same thing). In this case it is 3. Now you can make a general formula for it: It is the average of the top and bottom, multiplied by the width (4). So Area = (top + bottom)/2, then multiply that by the width. In this case its 40.

To help understanding it, think back to how you made it into a rectangle. The length ends up being 10 right? and what is the average of 7 and 13? 10! (7 + 13 = 20, 20/2 = 10)

Answer 3

Ok here is a more complex explanation

Area of a Trapezoid



If a and b are the lengths of the two parallel bases of a trapezoid, and h is its height, the area of the trapezoid is

1/2 × h × (a + b) .

To picture this, consider two identical trapezoids, and "turn" one around and "paste" it to the other along one side as pictured below:



The figure formed is a parallelogram having an area of h × (a + b), which is twice the area of one of the trapezoids.

Example:

What is the area of a trapezoid having bases 12 and 8 and a height of 5?

Using the formula for the area of a trapezoid, we see that the area is

1/2 × 5 × (12 + 8) = 1/2 × 5 × 20 = 1/2 × 100 = 50.

Here is an answer that is easier to understand.

A trapezoid is a 4-sided figure with one pair of parallel sides. To find the area of a trapezoid, take the sum of its bases, multiply the sum by the height of the trapezoid, and then divide the result by 2.

Here is me showing you with your problem.

your bases are 13 and 7

your hieght is 4

13 + 7 = 20

20 x 4 = 80

80/2 = 40

There should be some units (inches, feet) and it would be squared.

Answer 4

So, what grade are you in?

The equation to find the area of a trapezoid is (b1+b2)x.5h

b=base

h=height

1=1

2=2

Base 1 is usually the bottom, Base 2 is the top.

Answer 5

I hate online summer school too! I have 15 days to do a course now and I still can't manage to get off here.