the bases of an isosceles trapezium are 9cm and 21cm. if the diagnols are 17cm. find the area of the trapezium

Answer 1

In an isosceles trapezoid means the angled sides are equal in length.

You can find the height of the trapezoid by
17^2 = 15^2 + h^2

(the 17 is the diagonal, the 15 is the part of the 21cm base left when you drop the line for height. It's 15 because that longer base can be broken into 6+9+6. It makes more sense if you draw it.)

Anyway,
17^2 = 15^2 + h^2
289 = 225 + h^2
64 = h^2
8 = h

Now you can find the area:

A = (1/2)(h)(b1 + b2)
= (1/2)(8)(9 + 21)
= 4(30)
= 120

Answer 2

21-9=12
12/2=6

h^2+(6+9)^2=17^2

h^2=289-225
=64

h=8

area=(21+9)/2 * 8
=15*8=120

Answer 3

you recognize that the legs are congruent, and the backside angles are congruent. And whichever base you employ, that's congruent to itself. you will get congruent triangles, and then the diagonals are congruent by using corresponding factors.

Answer 4

...15cm square?