Help am dying Aa​

Aprojectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. after how many seconds does the projectile take to reach its maximum height?

Plz ( true - false) all triangles have interior angles whose measure sum to 90.

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?