William C. answered 09/18/23
Experienced Tutor Specializing in Chemistry, Math, and Physics
The total area of the pizza is πr2 = π(20)2 = 400π cm2
The pizza is cut into 6 slices since π/3 radians (60°) is 1/6 of 2π radians (360°) of a full circle.
So a slice of pizza has an area of 400π/6 cm2 = 200π/3 cm2
An equilateral triangle can be cut from the shared pizza slice so that it has half the area of the whole slice. This will be the half slice with no crust for Andre.
An equilateral triangle with side length x has area AΔ = (1/2)bh = (1/2)(x)((√3/2)x) = (√3/4)x2 cm2
Half the area of a pizza slice is (1/2)(200π/3) = 100π/3 cm2
to find length of the side of the equilateral triangle of the half slice with no crust set AΔ = 100π/3 cm2
AΔ = (√3/4)x2 = 100π/3
x2 = 400π/(3√3)
x = √[400π/(3√3)] = √[241.84] = 15.6 cm
answer
Cut a piece for Andre that is an equilateral triangle with side length 15.6 cm.
This piece will have no crust and will be half of the slice that it is cut from.


William C.
09/18/23
Doug C.
And since the central angle is 60 degrees, here is what the equilateral triangle could look like: desmos.com/calculator/yjum4m6tha09/18/23