Can anyone help me this problem about math?

Question

With a trapezoid, call c and d the bases, a and b the nonparallel sides. Prove this formula: A=((c+d)/2)*((a+b)/2)

in which A is the area.

Answer 1

er that formula is false and you cant prove it. i can disprove it for ya.
you have a trapezoid with legs a and b, and c and d being the bases. you know that a formula for a trapezoid is the average of the bases times the height: (h)(b1+b2)/2. (c+d)/2 is already the average of the bases, since c = b1 and d = b2. now you have to multiply it by the height. if the formula you're supposed to prove is true, then (a+b)/2 has to be equal to the height. how can that be possible? that will never happen unless you have BOTH of the of the legs are perpendicular to the bases. think about it. if they arent perpendicular to the bases, no matter how you draw the trapezoid, the average of the non parallel legs (a+b)/2 will always be greater than the height.

Answer 2

during summer, my brain just shuts down all nonessential functions such as proving mathematical functions, sorry.

But i am writing this as an answer, so I have to say something in response to the question. Remember to use theorems and postulates when writing proofs. Look at a list of postulates and see if any of them sound like the right one to start off ith, and if you're writing a two column proof, don't forget to begin with the "given!"

Answer 3

Try making some trapezoids into glued-together rectangles and triangles and calculate the area of each shape and add them together. That may lead you to a proof. Good luck!

Answer 4

A=((c+d)/2)*((a+b)/2)
A=(cd/2)*(ab/2)
A=cd + -.5 * ab + -.5
A= -cdab * 2

Answer 5

ummm what grade are u in



may i suggest a tutor at http://tutor.com

Answer 6

Do your own homework, buddy