What basic trigonometric identity would you use to verify that sin x cos x tan x =1 - cos^2 x

Can (3,5 and square root 34) be sides on a right triangle?

Need on this geometry question. explain how you did it.

Me solve this problem, and someone clearly explain to me how to solve it.1.) use the value of the discriminant to determine if the given trinomials has 2 real solutions, 1 real solution, or no real solutions.a.  x2  − 4x  − 7 = 0b. 4r2  + 11r  − 3 = 0c. 3m2  + 7 = 0d.  t2  + 2t  + 1 = 0