Let triangle $DEF$ be equilateral, where the side length is $3.$ A point $G$ is chosen at random inside the triangle. Find the probability that the length $DG$ is at most $1.$

Respuesta :

Answer:

13.43%

Step-by-step explanation:

see the attached figure to better understand the problem

we know that  

The probability that a point selected a random in triangle has distance from D to 1 or less is given by the area of the sector divided by the area of triangle

step 1

Find the area of sector

[tex]A_1=\frac{60}{360}\pi r^{2}[/tex]

we have

[tex]r=1\ unit[/tex]

substitute

[tex]A_1=\frac{60}{360}\pi (1)^{2}[/tex]

[tex]A_1=\frac{\pi}{6}\ unit^{2}[/tex]

step 2

Find the area of triangle

Applying the law of sines

The area of an equilateral triangle is equal

[tex]A_2=\frac{1}{2}b^2sin(60^o)[/tex]

we have

[tex]b=3\ units\\\\sin(60^o)=\frac{\sqrt{3}}{2}[/tex]

[tex]A_2=\frac{1}{2}(3)^2(\frac{\sqrt{3}}{2})[/tex]

[tex]A_2=9\frac{\sqrt{3}}{4}\ units^2[/tex]

step 3

Find the probability

[tex]P=\frac{A_1}{A_2}[/tex]

substitute

[tex]P=\frac{\pi}{6}:9\frac{\sqrt{3}}{4}[/tex]

[tex]P=\frac{4\pi}{54\sqrt{3}}[/tex]

assume

[tex]\pi =3.14[/tex]

[tex]P=\frac{4(3.14)}{54\sqrt{3}}=0.1343[/tex]

Convert to percentage

[tex]P=0.1343*100=13.43\%[/tex]

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