Answer:
see explanation
Step-by-step explanation:
Using the double angle identity for sine
sin2x = 2sinxcosx
Consider left side
cos20°cos40°cos80°
=
(2sin20°cos20°)cos40°cos80°
=
(2sin40°cos40°)cos80°
=
(sin80°cos80° )
=
(2sin80°cos80° )
=
. sin160°
=
. sin(180 - 20)°
=
. sin20°
=
= right side , thus proven
10/14 = 5/7
30/36 = 5/6
answer
not proportional
Answer:

Step-by-step explanation:
Take one polynomial from the other means to perform the sub.traction of them. Recall that it is better to use grouping symbols when subtracting polynomials, so we get the signs right when combining like terms:
The indicated subtraction is: 
Make sure that before removing the grouping symbol (parenthesis) that is preceded by a negative sign, we change the signs of every term inside it. Then combine like terms to get the final answer:

Which is the last option shown in the question
Answer:
x=1.25 and y=-5.5
Step-by-step explanation:
2x+y=-8, 2x=-y-8 or 4x=-2y-16. Plug this value in the second equation, we have - 2y-16-2y=6, y=-5.5. Plugging this in any equation we have, x=1.25
I think it's 112 I did it in my head might be wrong