Question

Solve

Answer 1

A cylinder of radius r cm and height h cm has a curved surface area A cm². Where –

• A = 2πrh cm²

a) We are asked to find formula for h.

$\qquad$$\purple{ \bf \longrightarrow A=2 \pi rh }$

First, overturn the equation

$\qquad$$\sf \longrightarrow 2 \pi rh =A$

Divide both sides by 2πr

$\qquad$$\sf \longrightarrow \dfrac{2\pi rh}{2\pi r } = \dfrac{A}{2\pi r}$

$\qquad$$\sf \longrightarrow \dfrac{\cancel{2 \pi r }h}{\cancel{2\pi r} } = \dfrac{A}{2\pi r}$

$\qquad$$\purple{\bf \longrightarrow h = \dfrac{A}{2 \pi r }}$

b) Again, we are given –

• Curved surface area, A = 93 cm²
• Radius, r = 2.5 cm
• π = 3.1

$\qquad\qquad\quad\underline{\sf{Substituting \ Values \ :}}$

⠀⠀⠀━━━━━━━━━━━━━━━━━━━━━━━━━━

$\qquad$$\bf \longrightarrow h = \dfrac{A}{2\pi r }$

$\qquad$$\sf \longrightarrow h = \dfrac{93}{2 \times 3.1 \times 2.5 }$

$\qquad$$\sf \longrightarrow h = \dfrac{93}{15.5}$

$\qquad$$\sf \longrightarrow h =\cancel{ \dfrac{93}{15.5}}$

$\qquad$$\pink{ \bf \longrightarrow h = 6\: cm }$

• Henceforth, height of the cylinder is 6 cm.

Answer 2

The Answer is Letter A.....