Which is more suitable for this problem (solution: there are a pair of parallel equilateral sides)

With this idea,

What we need to do next is to calculate when EQ and PC can be equal.

There is an analytical formula to get the length of AB, and if the abscissa of point C is known, the length of AC can also be calculated. The next step is to ask when the length of PC will be as long as that of QE.

This is the problem of distance, time and speed in mathematics.

Time t can be found by listing two actions.