Isosceles Trapezoid
A trapezoid is a special type of quadrilateral in which one pair of opposite sides are parallel.  In the above trapezium, AB is parallel to DC and AD & BC are non-parallel sides. It is also called as non isosceles trapezoid, since the non-parallel sides are not of equal lengths. |
Area of Isosceles Trapezoid
In the above trapezoid ABCD, Area of ABCD = Area of $\Delta$ABC + Area of $\Delta$ADC.
= $\frac{1}{2}$ x AB x h + $\frac{1}{2}$ x CD x h
= $\frac{1}{2}$ ( AB + CD ) x h
= $\frac{1}{2}$ x (sum of parallel sides ) x height
Isosceles Trapezoid Definition
A Trapezoid where two of the non-parallel sides measure equal lengths.
In the above trapezoid ABCD, AB is parallel to CD. The non-parallel sides AD and BC are of equal lengths.
(i.e) AD = BC.
Isosceles Trapezoid Properties
1. Only one pair of opposite sides are parallel. AB // DC.
2. The other pair of opposite sides are non-parallel BC is not parallel to AD.
3. (Isosceles trapezoid diagonals) The Diagonals of isosceles trapezoid are equal. (i.e) The diagonals AC = BD.
4. (Isosceles trapezoid angles) Two pairs of angles of isosceles trapezoid are equal.[ pairs of acute angles and pairs of obtuse angles are equal ]
(i.e) $\angle$A = $\angle$B and $\angle$C = $\angle$D.
5. Pairs Interior angles on the same side of the non-parallel sides and between the parallel lines are supplementary.[ sum of an acute + obtuse angle = 180° .
6. The sum of all the interior angles = 360°.