90+(2x+15)+x=180
90+2x+15+x=180
105+3x=180
3x=75
x=75/3
x=25degree
Check the picture below.
so is really just a thick trapezoid, or namely a trapezoidal prism 5 inches thick.
so if we just get the area of the trapezoidal face and multiply by the thickness, we'd get it's volume
![\bf \textit{area of a trapezoid}\\\\ A=\cfrac{h(a+b)}{2}~~ \begin{cases} a,b=\stackrel{parallel~sides}{bases}\\ h=height\\[-0.5em] \hrulefill\\ a = 8\\ b = 13\\ h = 6 \end{cases}\implies A=\cfrac{6(8+13)}{2}\implies A=63 \\\\\\ \stackrel{\textit{area of the trapezoidal prism}}{63\cdot 5\implies \stackrel{in^3}{315}}](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Barea%20of%20a%20trapezoid%7D%5C%5C%5C%5C%20A%3D%5Ccfrac%7Bh%28a%2Bb%29%7D%7B2%7D~~%20%5Cbegin%7Bcases%7D%20a%2Cb%3D%5Cstackrel%7Bparallel~sides%7D%7Bbases%7D%5C%5C%20h%3Dheight%5C%5C%5B-0.5em%5D%20%5Chrulefill%5C%5C%20a%20%3D%208%5C%5C%20b%20%3D%2013%5C%5C%20h%20%3D%206%20%5Cend%7Bcases%7D%5Cimplies%20A%3D%5Ccfrac%7B6%288%2B13%29%7D%7B2%7D%5Cimplies%20A%3D63%20%5C%5C%5C%5C%5C%5C%20%5Cstackrel%7B%5Ctextit%7Barea%20of%20the%20trapezoidal%20prism%7D%7D%7B63%5Ccdot%205%5Cimplies%20%5Cstackrel%7Bin%5E3%7D%7B315%7D%7D)
The cosine repeats itself every 360 degrees, and it mirrors at 0 and 180 degrees. It inverts around 90 and 270.
So without using a calculator, you can tell that:
cos(520)=cos(520-360)=cos(160)
cos(160) = cos(180-20) = cos(180+20) = cos(200)
cos(160) is NOT equal to cos(20), it would be -cos(20).
cos(160) = -cos(20) = -cos(-20)
So C is the only one unequal.
Answer:
He is 5.6 km away
Step-by-step explanation:
he starts traveling away from base and is 8.3 km away to start with
then he turns west and travels 13.9 km away
what this mean is that you have to subtract the distance he turned from the distance he started off with
ex: 13.9 - 8.3 = 5.9
to get your answer of how far away he is from the base