The diameter of acilindrical unshapen pencil 8mm and its length 17.5 cm find the surface area?
as with all cylinders of radius r and height (or length) h,
a = 2πr^2 + 2πrh = 2πr(r+h)
your radius is 4mm and length is 175mm, so plug and chug.
I will assume you meant:
a cylindrical unsharpened pencil ????
In that case, surface area is
2πr^2 + 2πrh
= 2π(4^2) + 2π(4)(175) mm^2
= 128π + 1400π mm^2
= 1528π mm^2 or 15.28π cm^2 -----> since 1 cm^2 = 100 mm^2
l want question
To find the surface area of a cylindrical pencil, you need to know the formula for the surface area of a cylinder. The formula for the surface area of a cylinder is:
Surface Area = 2πr(r + h)
where r is the radius of the cylinder and h is the height (or length) of the cylinder.
Now, we are given that the diameter of the cylindrical pencil is 8mm. The diameter is twice the radius, so we can find the radius by dividing the diameter by 2.
Radius = Diameter / 2 = 8mm / 2 = 4mm
Next, the length of the pencil is given as 17.5 cm. However, the radius is in mm, so we need to convert the length from cm to mm:
Length = 17.5 cm × 10 mm/cm = 175 mm
Now we can substitute the values into the formula to calculate the surface area:
Surface Area = 2π * 4mm * (4mm + 175mm)
Surface Area = 2π * 4mm * 179mm
Since the question doesn't specify to round the answer, we'll leave it in terms of π:
Surface Area ≈ 2 * 3.14 * 4mm * 179mm
Surface Area ≈ 3.14 * 8mm * 179mm
Surface Area ≈ 1422.56 mm²
Therefore, the surface area of the cylindrical pencil is approximately 1422.56 mm².