Answer:
Below in bold.
Step-by-step explanation:
Standard form is Ax + By = C
where A, B and C are integers and A must be positive.
So the first 2 are already in standard form but the last 2 can be converted to standard form by multiplying each term by -1:
-12x+3y=27
= -1*-12x + -1*3y = -1*27
12x - 3y = -27 is the answer.
The last one is:
24x + 12y = -60.
I'm sorry I'm not entirely sure. But I think -2 and 4. If it's not multiple choice I say -2.
Answer:
θ =
(60° )
Step-by-step explanation:
Using the identity
sin²x + cos²x = 1 ⇒ sin²x = 1 - cos²x
Given
cos²θ - sin²θ = 2 - 5cosθ
cos²θ - (1 - cos²θ) = 2 - 5cosθ
cos²θ - 1 + cos²θ = 2 - 5cosθ
2cos²θ - 1 = 2 - 5cosθ ( subtract 2 - 5cosθ from both sides )
2cos²θ + 5cosθ - 3 = 0 ← in standard form
(cosθ + 3)(2cosθ - 1) = 0 ← in factored form
Equate each factor to zero and solve for θ
cosθ + 3 = 0
cosθ = - 3 ← not possible as - 1 ≤ cosθ ≤ 1
2cosθ - 1 = 0
cosθ =
, so
θ =
(
) =
( or 60° )