Here Some Basic Formulas/Rules Are given below :-
Area of a rectangle = (Length x Breadth). so Length = ( ^{Area}/_{Breadth} ) and Breadth = ( ^{Area}/_{Length} )
Perimeter of a rectangle = 2 (Length + Breadth).
Area of a square = (side)^{2} = ^{1}/_{2}(diagonal)^{2}.
Area of 4 walls of a room = 2 (Length + Breadth) x Height.
Area of a triangle = ^{1}/_{2} X Base X Height.
Area of a triangle = √s (s - a) (s - b) (s - c) where a, b, c are the sides of the triangle and s = ^{1}/_{2} (a + b + c).
Area of an equilateral triangle = ^{√3}/_{4} X (side)^{2}
Radius of incircle of an equilateral triangle of side a = ^{a}/_{2√3}
Radius of circumcircle of an equilateral triangle of side a = ^{a}/_{√3}
Radius of incircle of a triangle of area Δ and semi-perimeter s = ^{Δ}/_{s}
Area of a parallelogram = (Base x Height).
Area of a rhombus = ^{1}/_{2} X (Product of diagonals).
Area of a trapezium = ^{1}/_{2} X (sum of parallel sides) X distance between them.
Area of a circle = πR^{2}, where R is the radius
Circumference of a circle = 2πR.
Length of an arc = = ^{2πRo}/_{360} where o is the central angle.
Area of a sector = = ^{1}/_{2} (arc X R) = ^{πR2o /360}
Area of a semi-circle = ^{πR2/2}
Circumference of a semi-circle = πR.
FUNDAMENTAL CONCEPTS :-
Results on Triangles :
Results on Quadrilaterals :