All basic formulas for trapezoid
Diagonal of an isosceles trapezoid
1. Diagonal of an isosceles trapezoid if you know sides (leg and bases)
, 
- bases
- leg (lateral side)
- diagonal
) :
2. Diagonal of an isosceles trapezoid using the law of cosines
, - bases
- leg (lateral side)
- diagonal
, 
- angles at the base
) :
3. Diagonal of an isosceles trapezoid if you know height, midsegment, area of a trapezoid and angle between the diagonals
, - bases
- diagonal
, - angles between the diagonals
- height
- midsegment
- area
) :
* It is true in this case:
4. Diagonal of an isosceles trapezoid if you know height, sides and angle at the base
- lower base
- upper base
- leg (lateral side)
- diagonal
- angle at the base
- height
) :
Midline of an isosceles trapezoid
1. Median of an isosceles trapezoid (also known as midline or midsegment) if you know bases
, - bases
- midline
) :
2. Median of an isosceles trapezoid (also known as midline or midsegment), if you know base, height and angles at the base
- lower base
- upper base
- leg (lateral side)
- angle at the base
- height
- midline
) :
3. Median of an isosceles trapezoid (also known as midline or midsegment), if you know diagonal, height and angle between the diagonals
- diagonal
, - angles between the diagonals
- height
- midline
) :
4. Median of an isosceles trapezoid (also known as midline or midsegment), if you know area of a trapezoid and height or lateral side and angle at the base
- areaof a trapezoid
- leg (lateral side)
- height
- angle at the base
- midline
) :
Height of an isosceles trapezoid
1. Height of an isosceles trapezoid if you know only sides or sides and angle at the base
, - bases
- leg (lateral side)
- angle at the base
- height
) :
) :
2. Height of an isosceles trapezoid if you know diagonal, angle between the diagonals and bases or midline
, - bases
- diagonals
, - angles between the diagonals
- midline
- height
) :
) :
3. Height of an isosceles trapezoid if you know area of a trapezoid
, - bases
- area
- midline
- height
) :
Sides (bases) of a right trapezoid
1. Side (base) of a right trapezoid if you know other base and midline of a trapezoid
, - bases
- midline
2. Sides (bases) of a right trapezoid if you know lateral sides, angle at the base and other base
, - bases
- lateral side = height
- lateral side
- angle at the base
3. Sides (bases) of a right trapezoid if you know diagonals, lateral side (height) and angle between the diagonals
, - bases
- lateral side = height
, 
- diagonals
, - angles between the diagonals
* It is true in this case:
4. Sides (bases) of a right trapezoid if you know area of a trapezoid, lateral side (height) and other base
, - bases
- lateral side = height
- height
- area
* It is true in this case:
