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A conical paper cup is to have a height of 3 inches. Find the radius r of the cone that will result in a surface area of 6 in2.
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Answer:

The radius of the conical cup is 1.95 in.

Step-by-step explanation:

Given:

Height of the conical cup is [tex]h=3[/tex] inches.

Area or curved surface area of the cup is [tex]A=6\rm{in^{2}}[/tex]

Let the radius of the cup is [tex]r[/tex].

Now, the lateral height [tex]l[/tex] of the cone will be,

[tex]l=\sqrt{r^{2}+h^{2}}\\l=\sqrt{r^{2}+3^{2}}[/tex]

The curved surface area of the cone is,

[tex]A=\pi rl\\6=\pi r \sqrt{r^{2}+9}\\r \sqrt{r^{2}+9}=1.91[/tex]

Squaring the both sides,

[tex]r^{2} (r^{2}+9)=3.6[/tex]

Now, let [tex]r^{2}=x[/tex] and solve the resulting quadratic equation.

[tex]x (x+9)=3.6\\x^{2}+9x-3.6=0[/tex]

Solving the above quadratic equation as,

[tex]x=\frac{-b\pm \sqrt{b^{2}-4ac}}{2a}\\x=\frac{-9\pm \sqrt{9^{2}-4\times1\times(-3.6)}}{2\times9}\\x=0.38, -9.38[/tex]

Now, the value of [tex]x[/tex] cannot be negative as it is the square of radius.

So, the value of radius of the cone will be,

[tex]r=\sqrt{x}\\r=\sqrt{0.38}\\r=1.95\rm{in}[/tex]

Therefore, the radius of the conical cup is 1.95 in.

For more details, refer the link,

https://brainly.com/question/12267785?referrer=searchResults