A piece of wood is designed in the shape of a cone

A cylindrical hole of radius 4cm and depth 2 cm has been drilled into the base,

The surface area of the piece of wood has to be painted, except from the area inside the hole.

work out the surface area to be painted

give your answer in terms of pi, thank you sooo much

Surface area of the wood to be painted =  ( + r ) - 16

Step-by-step explanation:

Surface area of a cone is given as the sum of the surface area and the area of its base.

     i.e    Surface area = + Lr

where: L is the length of its slant height and r is the radius.

Applying the Pythagoras theorem,

                        L =

Thus,

                Surface area  =  r (r + )

The given cylindrical hole has a radius of 4 cm and depth 2 cm.

The area of one of its circular surfaces =

                                                   = ×

                                                   = 16

The surface area of the piece of wood to be painted = surface area of cone - area of cylindrical circular surface.

Surface area of the wood to be painted = r (r + ) - 16

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation: