Triangle ABC is equilateral with side length 3. A point X is randomly chosen within △ABC. What is the probability that X is no more than 1 unit away from vertex A?
Answered here.
https://web2.0calc.com/questions/help_3820
Plenty of answers to choose from :D
-π KeyLimePi
Here's equilateral triangle ABC and a circle with radius 1 centered on point A:
The intersecion of the triangle and the circle is the highlighted sector.
probability that a randomly chosen point lands in highlighted sector = area of sector / area of triangle
So we just have to find the area of the sector and the area of the triangle.
Let's find the area of the sector:
area of sectorarea of circle = measure of central angle360∘ area of sectorπ⋅12 = 60∘360∘ area of sector = 60∘360∘⋅π⋅12 area of sector = π6
Now let's find the area of the triangle:
area of triangle = 12⋅base⋅height area of triangle = 12⋅3⋅3√32 area of triangle = 9√34
Now we can find the probability in question.
probability=area of sectorarea of triangle probability=area of sector÷area of triangle probability=π6÷9√34 probability=π6⋅49√3 probability=4π54√3 probability=4√3π162 probability=2√3π81_