<span>Here you go:
1) Applying (a + b)² = a² + b² + 2ab,
(cosx + cosy)² = cos²x + cos²y + 2cos(x)*cos(y) and
(sinx + siny)² = sin²x + sin²y + 2sin(x)*sin(y)
2) ==> (cosx + cosy)² + (sinx + siny)² =
= (cos²x + sin²x) + (cos²y + sin²y) + 2{cos(x)cos(y) + sin(x)sin(y)}
= 2 + 2{cos(x - y)} = 2[1 + cos(x - y)]
= 2*2cos²{(x - y)/2} [Multiple angle identity, 1 + cos(2A) = 2cos²A]
= 4*cos²{(x - y)/2} [Proved]</span>
We replace y with 2x -4 in the second.one to solve the system so we have
x+3(2x-4)=5
x+6x-12=5
7x=17
x=17/7 so no, (2,0) is not the solution
Answer:
210
Step-by-step explanation:
7*6 = 42
42*5 = 210
Answer:
2/8 is your answer
Step-by-step explanation:
I just got that question in one my tests. Hope this was helpful
Answer:
13 boards.
Step-by-step explanation:
1st, sume the sides of the triangle.
17 + 13 + 8.5 = 38.5ft
If one board is 3ft long, then 38.5ft/3ft=12.83≈ 13 boards!
