A group of learners in senior high school plans to make an igniter using the rays of the sun. The learners plan to use a concave (parabolic) mirror having a diameter of 10𝑑𝑛 and 2𝑑𝑛 deep. At what point should the put the ignite? Why?

Answer 1

If the equation of the parabola is
x^2 = 4py
and contains the point (5,2) then
25 = 8p
and p = 25/8
The focus is at (0,p)