Answer: B. 1178 cm²
What we are solving for:
The lateral area is, put simply, the surface area of the cone not including the bottom.
The formula is:
L = πr[tex]\sqrt{h^{2} +r^{2} }[/tex]
Height of the cone:
This calls for the height, since it is a right triangle we can use the Pythagorean theorem to solve.
a² + b² = c²
15² + b² = 25²
225 + b² = 625
b² = 400
b = [tex]\sqrt{400}[/tex]
The height is 20 cm
Solving:
Back to the formula,
L = πr[tex]\sqrt{h^{2} +r^{2} }[/tex]
L = π15[tex]\sqrt{(20)^{2} +(15)^{2} }[/tex]
L ≈ 1178.1 cm²
The lateral area of the cone is B. 1,178 cm².
