Answer:
cos0 = 1
cos90 =0
so a for the first one and d for the other
There are mnemonic acronyms out there for reminding you how to do this. I think of it simply as using the distributive property.
(4x-3)(x+5) = 4x(x+5) -3(x+5)
then again
= (4x² +20x) + (-3x -15)
= 4x² + (20-3)x -15 . . . . . . . combine like terms
= 4x² +17x -15
30,000 - 19,500 = 10,500 gallons left to fill the pool. So I am assuming the answer would be w = 10,500 gallons... unless there was an equation missing in the question
5(a + 3b) = 5(9 + 3(2)) = 5(9 + 6) = 5(15) = 75
