Types of quadrilaterals:
Rectangle: A four sided polygon having all right angles is known as rectangle. The sum of the angles of a rectangle is 360 degrees.
(or)
A rectangle is a parallelogram with four right angles, two pairs of congruent opposite sides, and two congruent diagonals.
From the above figure,
- [latex]\overline{AB} \parallel \overline{DC}[/latex]
- [latex]m \overline{AB}[/latex] = [latex]m \overline{DC}[/latex]
- [latex]m \overline{AC}[/latex] = [latex]m \overline{BD}[/latex]
- [latex]m\angle[/latex]A = [latex]m\angle[/latex]B = [latex]m\angle[/latex]C = [latex]m\angle[/latex]D = [latex]{90}^{\circ}[/latex]
Properties of rectangle:
- All four angles of a rectangle are right angles.
- The diagonals of a rectangle are congruent.
The perimeter of a rectangle is twice the sum of its length and width i.e.
Perimeter = 2([latex]a[/latex] + [latex]b[/latex])
The area is the product of the length and width i.e.
Area = [latex]a[/latex] x [latex]b[/latex]
Square:
Rectangle of equal sides is known as a square.
(OR)
A square is a parallelogram with four congruent sides and four congruent angles.
From the figure above,
- [latex]\overline{AB} \parallel \overline{DC}[/latex]
- [latex]m \overline{AB}[/latex] = [latex]m \overline{DC}[/latex]
- [latex]m \overline{AC}[/latex] = [latex]m \overline{BD}[/latex]
- [latex]m\angle[/latex]A = [latex]m\angle[/latex]B = [latex]m\angle[/latex]C = [latex]m\angle[/latex]D = [latex]{90}^{\circ}[/latex]
If the side of the square is [latex]a[/latex], then
The perimeter of a square = [latex]a[/latex] + [latex]a[/latex] + [latex]a[/latex] + [latex]a[/latex] = 4[latex]a[/latex]
Area of a square = [latex]a[/latex] x [latex]a[/latex] = [latex]a^2[/latex]
- Diagonals bisect each other at right angles and are equal in length.
- Diagonals bisect the vertex angles to create [latex]{45}^{\circ}[/latex] angles.
- Formula for the area of a square is A = [latex]a^2[/latex].
- formula for perimeter of a square is P = 4[latex]a[/latex].
For example, let [latex]a[/latex] is the length of a side of square.
If length is known, calculating the length of the diagonal is easy i.e.
From the above figure,
Since [latex]d[/latex] is the hypotenuse of the 45-45-90 triangle which has legs of length 5,
according to the ratio 1 : 1 : [latex]\sqrt{2}[/latex]
Hence, diagonal [latex]d[/latex] = 5[latex]\sqrt{2}[/latex].
Parallelogram: Parallelogram is a convex quadrilateral with one pairs of parallel sides. Altitude (or height) is the segment perpendicular to the base. Special parallelograms are rectangles, squares and rhombuses.
From the above figure,
Perimeter of a parallelogram is the sum of its sides i.e.
Perimeter = [latex]a[/latex] + [latex]b[/latex] + [latex]a[/latex] + [latex]b[/latex] = 2([latex]a[/latex] + [latex]b[/latex])
The area is the product of the base and height i.e.
Area = [latex]b[/latex] x [latex]h[/latex]
Rhombus: A four-sided polygon having all four sides of equal length is known as rhombus. The sum of the angles of a rhombus is 360 degrees.
(OR)
A rhombus is a parallelogram with two pairs of congruent opposite angles, four congruent sides, and two perpendicular diagonals that bisect the angles of a rhombus.
From the above figure,
- [latex]\overline{AB} \parallel \overline{DC}[/latex]
- [latex]m \overline{AB}[/latex] = [latex]m \overline{BC}[/latex] = [latex]m \overline{CD}[/latex] = [latex]m \overline{DA}[/latex]
- [latex]\overline{AD} \parallel \overline{BC}[/latex]
- [latex]AC \perp BC[/latex]
- [latex]m\angle[/latex]A = [latex]m\angle[/latex]C
- [latex]m\angle[/latex]ABO = [latex]m\angle[/latex]CBO =[latex]m\angle[/latex]ADO = [latex]m\angle[/latex]CDO
- [latex]m\angle[/latex]B = [latex]m\angle[/latex]D
- [latex]m\angle[/latex]BAO = [latex]m\angle[/latex]DAO =[latex]m\angle[/latex]BCO = [latex]m\angle[/latex]DCO
The perimeter of a rhombus is the quadruple of its side i.e.
Perimeter = [latex]s[/latex] + [latex]s[/latex] + [latex]s[/latex] + [latex]s[/latex] = 4[latex]s[/latex]
The area is the product of the diagonals i.e.
Area = [latex]\frac{a * b}{2}[/latex]
Trapezoid:
- Trapezoid is a convex quadrilateral with exactly one pair of parallel sides.
- Bases are the parallel sides, and the legs are non parallel sides.
- Altitude (or height) is the segment perpendicular to the bases.
- Median is the segment connecting the mid points of the legs.
- Trapezoid with congruent legs is an isosceles trapezoid. Since legs are congruent, both pairs of the base angles are also congruent.
- The sum of the measures of the four interior angles is always 360 degrees. Further more, the same side interior angles between the bases are supplementary.
[latex]m\angle[/latex]A + [latex]m\angle[/latex]B + [latex]m\angle[/latex]C + [latex]m\angle[/latex]D = [latex]{360}^{\circ}[/latex]
[latex]m\angle[/latex]A + [latex]m\angle[/latex]D = [latex]{180}^{\circ}[/latex]
[latex]m\angle[/latex]B + [latex]m\angle[/latex]C = [latex]{180}^{\circ}[/latex]
The perimeter of a trapezoid is the sum of its sides i.e.
Perimeter = [latex]a[/latex] + [latex]b[/latex] + [latex]c[/latex] + [latex]d[/latex].
The area of a trapezoid is one half of the product of its height and the sum of bases i.e.
Area = [latex]\frac{1}{2}[/latex] x ([latex]b[/latex] + [latex]d[/latex]) x [latex]h[/latex].