How to find the area of a cone

Topic : Area of Cone

A cone is a three-dimensional geometric shape that tapers smoothly from a flat, round base to a point called the apex or vertex. More precisely, it is the solid figure bounded by a plane base and the surface (called the lateral surface) formed by the locus of all straight line segments joining the apex to the perimeter of the base


Question:

SA = LA + B

= πrl + πr2
    1
V = --- r2
    3

Find LA,B,SA and V for the cone with dimensions: d = 5cm and 1 = 6cm

Answer:

            d     5
d = 5cm r = --- = --- = 2.5cm
            2     2
l = 6cm

LA = πrl = 3.14*2.5*6 = 2.5cm2

B = πr2 = 3.14*2.5*2.5 = 19.63cm2

SA = LA + B = 47.1 + 19.63 = 66.73cm2

h = √l2 r2

= √(6)2 - (2.5)

= √36-6.25

= 5.45cm


    1               
v = --- πr2
    3

    1
h = --- *3.14*(2.5)2*5.45
    3

= 35.65cm3