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Geometry Mathematical Formulas

Geometry Mathematical Formulas

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<strong>Geometry</strong><br />

Important <strong>Mathematical</strong> <strong>Formulas</strong><br />

1. Pythagoras Formula : h 2 = p 2 + b 2 => h = 풑 ퟐ + 풃 ퟐ<br />

p 2 = h 2 – b 2 => p = √풉 ퟐ − 풃 ퟐ<br />

b 2 = h 2 – p 2 => b = 풉 ퟐ − 풑 ퟐ<br />

2. Perimeter of a triangle = sum of the length of its three sides<br />

Perimeter of an equilateral triangle = 3 × sides<br />

3. Perimeter of a rectangle = 2(length + breadth)<br />

Length = 퐩퐞퐫퐢퐦퐞퐭퐞퐫<br />

ퟐ<br />

Breadth = 퐩퐞퐫퐢퐦퐞퐭퐞퐫<br />

ퟐ<br />

4. Perimeter of a square = 4 × side<br />

Length of side = 퐩퐞퐫퐢퐦퐞퐭퐞퐫<br />

ퟒ<br />

5. Perimeter of a rhombus = 4 × side<br />

– breadth<br />

– length<br />

Length of side = 퐩퐞퐫퐢퐦퐞퐭퐞퐫<br />

ퟒ<br />

6. Perimeter of a parallelogram = 2 ×(sum of two adjacent sides)<br />

7. Circumference of a circle = 2훑r<br />

8. Perimeter of a semicircle = r(훑 + 2)<br />

9. Area of a triangle = ퟏ<br />

× base × height<br />

ퟐ<br />

10. Area of a rectangle = length × breadth<br />

Length = 퐀퐫퐞퐚<br />

퐁퐫퐞퐚퐝퐭퐡<br />

11. Area of a square = side × side<br />

Side of a square = √퐀퐫퐞퐚<br />

12. Area of a parallelogram = Base × Height<br />

13. Area of a rhombus = ퟏ<br />

Breadth= 퐀퐫퐞퐚<br />

퐋퐞퐧퐠퐭퐡<br />

ퟐ × d1 × d2 [where, d1 and d2 are two diagonals]


14. Area of a trapezium = ퟏ<br />

× (a + b) × h [where, 'a' and 'b' are two parallel<br />

ퟐ<br />

sides and 'h' is height]<br />

15. Area of a circle = 훑r 2<br />

16. Lateral Surface Area of a cuboid = 2 × (l + b) × h<br />

Total Surface Area of a cuboid = 2 × (lb + bh + lh)<br />

Diagonal of a cuboid = √퐥 ퟐ + 퐛 ퟐ + 퐡 ퟐ<br />

17. Lateral Surface Area of a cube = 4 × l 2<br />

Total Surface Area of a cube = 6 × l 2<br />

Diagonal of a cube = l√ퟑ<br />

18. Curved Surface Area of a solid cylinder = 2훑퐫퐡<br />

Total Surface Area of a solid cylinder = 2훑r 2 +2훑퐫퐡<br />

= 2훑r (r + h)<br />

Curved Surface Area of a hollow cylinder = 2훑퐑퐡 + 2훑퐫퐡 = 2훑퐡(R + r)<br />

Surface Area of a hollow cylinder = 2훑퐫퐡 + 2훑퐑퐡 + 2(훑R 2 – 훑r 2 )<br />

Area of the ring = 훑R 2 – 훑r 2 = 훑(R 2 – r 2 )<br />

Thickness of the ring = R – r<br />

19. Curved Surface Area of a cone = 훑퐫퐥 [where, l = slant height]<br />

Total Surface Area of a cone = 훑r 2 + 훑퐫퐥 = 훑r (r + l)<br />

20. Surface Area of a sphere = 4훑r 2<br />

Surface Area of a hemisphere = 3훑r 2<br />

21. Surface Area of a prism = 2 × area of base + perimeter of base × height<br />

22. Surface Area of any pyramid = area of base + area of each of lateral faces<br />

23. Surface Area of regular pyramid = area of base + ퟏ<br />

24. Surface Area of square pyramid = b 2 + 2bs<br />

ퟐ<br />

× ps<br />

Where, p = perimeter of the base<br />

s = slant height<br />

[Where, b = length of the base, s = slant height]

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