Find the vertex of this function
f(x)= x^2+4x-12

When keisha installed a fence along the 200 foot perimeter of her rectangular back yard, she left an opening for a gate.in the diagram below, she used x to represent the length in feet of the gate? what is the value? a. 10 b. 20 c. 25 d. 30

If you could answer these your a life saver

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.