Answer:

Step-by-step explanation:
Using the addition formulae for cosine
cos(x ± y) = cosxcosy ∓ sinxsiny
---------------------------------------------------------------
cos(120 + x) = cos120cosx - sin120sinx
= - cos60cosx - sin60sinx
= -
cosx -
sinx
squaring to obtain cos² (120 + x)
=
cos²x +
sinxcosx +
sin²x
--------------------------------------------------------------------
cos(120 - x) = cos120cosx + sin120sinx
= -cos60cosx + sin60sinx
= -
cosx +
sinx
squaring to obtain cos²(120 - x)
=
cos²x -
sinxcosx +
sin²x
--------------------------------------------------------------------------
Putting it all together
cos²x +
cos²x +
sinxcosx +
sin²x +
cos²x -
sinxcosx +
sin²x
= cos²x +
cos²x +
sin²x
=
cos²x +
sin²x
=
(cos²x + sin²x) = 
Answer:
95% Confidence interval for the variance:

95% Confidence interval for the standard deviation:

Step-by-step explanation:
We have to calculate a 95% confidence interval for the standard deviation σ and the variance σ².
The sample, of size n=8, has a standard deviation of s=2.89 miles.
Then, the variance of the sample is

The confidence interval for the variance is:

The critical values for the Chi-square distribution for a 95% confidence (α=0.05) interval are:

Then, the confidence interval can be calculated as:

If we calculate the square root for each bound we will have the confidence interval for the standard deviation:

Answer:
x = -4
Step-by-step explanation:
Plug in -4 into the function and solve for x:
f(x) = 6x + 20
-4 = 6x + 20
-24 = 6x
-4 = x
So, the answer is x = -4
Answer:
• linear angles
• supplementary angles (all linear angles are supplementary)
Step-by-step explanation:
If the angles share a side and are measured in opposite directions from that side, the non-common edges of these angles form a straight line, so these angles are sometimes called "linear" angles.
Since their sum is 180°, they are always "supplementary" angles. (Supplementary angles need not share a vertex or a side.)