MENSURATION
PYTHAGORAS’ THEOREM
For all the right angled triangles “ the square on the hypotenuse is equal to the
sum of the squares on the other two sides”
                                                𝑐 2 = 𝑎2 + 𝑏 2
𝒄 = 𝑎2 + 𝑏 2                     𝒃 = 𝑐 2 − 𝑎2                   𝒂 = 𝑐 2 − 𝑏2
Area and Perimeter:
    Figure               Diagram                                Area                    Perimeter
Rectangle
                                     b       Area = l × b                      perimeter = 2( 𝑙 + 𝑏 )
                        l
Square                       a
                  a              a
                                             Area = side × side                perimeter = 4 × side
                         a                       = a×a                                 =4×a
Parallelogram                                 Area = b × h
                                                                               perimeter = 2(a + b )
                                              Area = ab sin 𝜃
                                             where a, b are sides and 𝜃 is
                                             the included angle
Triangle
                                                        1
                                               Area =       × 𝑏𝑎𝑠𝑒 × 𝑒𝑖𝑔𝑡
                                                        2
                                                            1
                                                Area = 2 𝑎𝑏 𝑠𝑖𝑛 𝐶              perimeter = a + b + c
                                                = 𝑠 𝑠 − 𝑎 𝑠 − 𝑏 (𝑠 − 𝑐)
                                                                𝑎+𝑏+𝑐
                                                where s =
                                                                  2
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Trapezium
                                                                       perimeter = Sum of all
                                             1
                                    Area = 2 𝑎 + 𝑏                              sides
Circle
                         r
                                    Area =  r2                        circumference = 2  r
Semicircle                                   1 2                                  1
                                    Area =     r                      perimeter =  d + d
                         r                   2                                    2
Sector               𝑟                                                                            
                                    Area =  r  360                   length of an arc = 2 r 
                                              2
                   𝜃                                                                               360
Surface Area and Volume:
      Figure          Diagram                    Surface Area                       Volume
  Cylinder
                                                                         Volume =  r h
                                                                                     2
                                   curved surface area = 2πrh
                                   total surface area = 2πr(h + r)
  Cone                             curved surface area = 𝜋𝑟𝑙                        1 2
                                                                         Volume =     πr h
                                   where l = (r 2  h 2 )                           3
                                   total surface area = 𝜋𝑟(𝑙 + 𝑟)
  Sphere                                                                            4 3
                                                                         Volume =     πr
                                   Surface area = 4πr2                              3
  Pyramid                                                                         1
                                                                         Volume =   × base area ×
                                   Base area + area of the shapes in              3
                                   the sides                             perpendicular height
  Cuboid
                                   Surface area = 2(𝑙𝑏 + 𝑏 + 𝑙)        Volume = 𝑙 × 𝑏 × 
  Cube
                                   Surface area = 6𝑙 2                   Volume = 𝑙 3
                                                                                    2 3
  Hemisphere                       Curved surface area = = 2 r2         Volume =     r
                                                                                    3
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