All equilateral triangles are isosceles, true or false

a. 15 meters.

b. 20 meters.

Step-by-step explanation:

a. The height of the ball at 3 seconds. 20 * 3 - 5 * (3)^2 = 60 - 5 * 9 = 60 - 45 = 15.

The ball will be 15 meters high.

b. The maximum height reached by the ball.

To get that, we need to find the vertex of the parabola. We do so by doing -b/2a to find the x-coordinate of the vertex.

In this case, a = -5 and b = 20.

-20 / 2(-5) = -20 / -10 = 20 / 10 = 2.

Then, we find the y-coordinate by putting 2 where it says "t".

h(2) =  20(2) - 5(2)^2 = (40) - 5(4) = 40 - 20 = 20 meters.

Hope this helps!