Equilateral triangle EKP with side EK of length 2 inches is placed inside square EAMI with side of length 4 inches so that K is on side EA. The triangle is rotated clockwise about K, then P, and so on along the sides of the square until E, K, and P return to their original positions. The length of the path in inches traversed by vertex P is equal to:
- 20
/3 - 32/3
- 12
- 40/3
- 15
Our point P makes a lengthy journey, with many stops, before returning home. Some moves, which we call “a”, as from P to A, are 120° around a circle of radius 2. The length of an “a” move is · 2) = 4/3.
Shorter moves, which we call “c”, as from B to C, are 30°; their length is · 2) = /3.
When P lands in corners or on edges, it pauses briefly.
We have 8 “a” moves and 8 “c” moves. The total trip is 8(4/3) + 8(/3) = 40/3. The answer is (d).