Yes, it is a linear equation.
Answer:
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
<h2><u>Solution</u>:-</h2>
• Surface area of a cylinder = 2πr(r + h) sq. units.
In the above diagram,
Radius (r) of the cylinder = 13 cm.
Height (h) of the cylinder = 39 cm.
<h3>• Taking value of π = 3.14</h3>
Hence, Surface area of the cylinder = 2 × 3.14 × 13(13 + 39)
Surface area of the cylinder = (81.64 × 52) cm²
Surface area of the cylinder = 4245.28 cm²
The surface area of the cylinder is <u>4</u><u>2</u><u>4</u><u>5</u><u>.</u><u>2</u><u>8</u><u> </u><u>cm²</u>. [Answer]