SOLUTION: which expression represents the area of the trapezoid at right?(shows a isolsceles trapeziod with the short base labled with "a" opposite to that base is "b" which is parallel to "

Question 444084: which expression represents the area of the trapezoid at right?(shows a isolsceles trapeziod with the short base labled with "a" opposite to that base is "b" which is parallel to "a" and finally side "c"(4 sides).no height given.only one angle given 30 degrees.
A. c(a+b)divided by 4
B. c(a+b)divided by 2
C. bc divided by 2
D. a+b+c divided by 2
PLEASE EXPLAIN
Answer by cleomenius(959) (Show Source): You can put this solution on YOUR website!
I do not believe any answer is correct, b would work if you were using the height instead of side c.
I do not believe we could find the height unless we know which angle is the 30 degree angle.
I did find, however a formula for finding the height of an isosceles triangle using the sides without the angles that should work.
h = sqtr of ( c^2 - 1/4( b - a)^2 )

This was obtained from http://mathworld.wolfram.com/IsoscelesTrapezoid.html

If this value is replaced for c in choice b, that should give your result.
Cleomenius.

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