### Maths Formulas for Class 8

Many students consider mathematics as a scary subject and math formulas are often difficult to remember when you don’t understand them well. The negative approach towards any subjects will make a student reluctant to study that particular subject.Usually students feel jittery during the exam time and they fail to give their best shot. To make things easier and guide through different concepts in Maths, we will discuss the important CBSE Class 8 math formulas here.

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** Algebraic Expansions:**

^{2}= a

^{2}+ 2ab + b

^{2}

^{2 }= a

^{2}– 2ab + b

^{2}

^{2}– b

^{2}

^{2}+ (a + b)x + ab

^{2}+ (a – b)x – ab

^{2}+ (b – a)x – ab

^{2}– (a + b)x + ab

^{3}= a

^{3}+ b

^{3}+ 3ab(a + b)

^{3}= a

^{3}– b

^{3}– 3ab (a – b)

^{2}= x

^{2}+ y

^{2}+ z

^{2}+ 2xy + 2yz + 2xz

^{2}= x

^{2}+ y

^{2}+ z

^{2}+ 2xy – 2yz – 2xz

^{2}= x

^{2}+ y

^{2}+ z

^{2}– 2xy – 2yz + 2xz

13. (x – y – z)^{2} = x^{2} + y^{2} + z^{2} – 2xy + 2yz – 2xz

Temperature Conversions :

ºC = 5959 ( ºF – 32 ) ºF = 9595 ( ºC + 32 )

**Simple Interest ** = P X T X R / 100

**Pythagorean Theorem:
**

a

^{2 }+ b

^{2}= c

^{2}

**Laws of Exponents**

Dividing Powers with Same Base

Negative Powers

**Geometrical Formula:**

Sl.No | Figure | Formula for surface area | Formula for volume |

1 | Rectangular Prism | SA = 2ab+2bc+2ca sq. units where a, b,c are the sides of the cube. | V = abc cubic units |

2 | Cylinder | SA = 2πrh sq. units TSA = 2πr(h+r) sq. units r =radius of the cylinder h – height of the cylinder | V = πr^{2}h cubic units |

3 | Cube | SA = 6a ^{2} sq. units a = sides of the cube | V = a^{3} cubic units |

4 | Sphere | SA = 4πr ^{2} sq. units r = radius of the sphere | V = 4343πr^{3 } cubic units |

5 | Ellipsoid | SA = 4π[(apbp+apcp+bpcp)3]1p4π[(apbp+apcp+bpcp)3]1p p = 1.6075 a, b, c are semi axis of ellipsoid | V = 4343 π r_{1},r_{2},r_{3} cubic units |

6 | Cone | CSA = πr1 sq.units | V = 1313πr^{2}h cubic units |

7 | Pyramid | SA = a+1212*p*l p = perimeter of pyramid l = slant height a = area of the base of the pyramid | V = 1313*a*h cubic units |

8 | Torus | SA = π ^{2} * (R^{2} – r^{2}) R:Outer Radius r: Inner Radius | V = 1414π^{3} (r_{1}+r_{2}) (r_{1}-r_{2})^{2} cubic units |

9 | Hemisphere | CSA = 2πr ^{2} TSA = 3πr ^{2 } r = radius | V = 2323 πr^{3} cubic units |

10 | Triangle | SA = s(s−a)(s−b)(s−c)‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾√s(s−a)(s−b)(s−c) where s is the perimeter of the triangle a, b, c are the sides of the triangle | |

11 | Rectangle | A = l*w L = length w = width | |

12 | Triangle | A = 1212bh b = base h = height | |

13 | Trapezoid | A = 1212 h (b_{1}+b_{2}) | |

14 | Parallelogram | A = bh | |

15 | Circle | A = πr^{2} r = radius |