Form 1

SOLID GEOMETRY

(a) Area and perimeter

Triangle

A = 1/2 ´ base ´ height

   = 1/2bh

Trapezium

A = 1/2 (sum of two parallel sides) ´ height

   = 1/2 (a + b) ´ h

Circle

Area = pr2

Circumference = 2pr

Sector

Area of sector = q/360 x pr2

Length of arc = q/360 x 2pr

Cylinder

Curve surface area = 2prh

Sphere

Curve surface area = 4pr2

(b) Solid and Volume

Cube:

V = x ´ x ´ x = x3

Cuboid:

V = l ´ b ´ h

= lbh

Cylinder

V = p r2h

Here is another examples of solid geometry .

POLYGON

(a) The sum of the interior angles of a n sided polygon

     = (n – 2) x 180°

(b) Sum of exterior angles of a polygon = 360°

(c) Each exterior angle of a regular n sided polygon = 360°/n

(d) Regular pentagon 

     Each exterior angle = 72°

      Each interior angle = 108°

(e) Regular hexagon

     Each exterior angle = 60°

     Each interior angle = 120°

(f) Regular octagon 

     Each exterior angle = 45°

     Each interior angle = 135°