How can you use bar diagrams to compare quantities in real world situation

Can any one me with the answers to these questions asap?

Describe the 2 algebraic methods you can use to find the zeros of the function f(t)=-16t^2+400.

In right ∆abc shown below, the midpoint of hypotenuse ac is located at d and segment bd is drawn. if ab = 12 and bc = 16, then explain why bd = 10. hint: consider what you know about the diagonals of a rectangle.