solve each triangle. if there are two triangles solve them both. A= 9 degrees 52' a= 3761ft b=5293ft
@jim_thompson5910
|dw:1460072914426:dw|
|dw:1460072943762:dw|
9 degrees, 52 arcminutes = 9+(52/60) = 9.86667 degrees approx |dw:1460073034806:dw|
to find x, you'll need to use the law of cosines. Are you familiar with that formula?
sin9.8667/x = sin a/ 3761
no you're thinking of the law of sines
whats law of cosine then
the law of sines cannot be used yet. We need to figure out x first actually now that I think about it, we can use the law of sines to find angle B
how do we do that?
let's use the law of sines to find angle B \[\Large \frac{\sin(B)}{b} = \frac{\sin(A)}{a}\] \[\Large \frac{\sin(B)}{5293} = \frac{\sin(9.86667)}{3761}\] does that help at all?
0.645
how are you getting that?
i plugged that equation into the calculator
\[\large \frac{\sin(B)}{5293} = \frac{\sin(9.86667^{\circ})}{3761}\] \[\large 3761*\sin(B) = 5293*\sin(9.86667^{\circ})\] \[\large \sin(B) = \frac{5293*\sin(9.86667^{\circ})}{3761}\] \[\large \sin(B) \approx 0.2411559\] \[\large B \approx \arcsin(0.2411559) \ \text{ or } \ B \approx 180-\arcsin(0.2411559)\] \[\large B \approx 13.95477255^{\circ} \ \text{ or } \ B \approx 166.045227^{\circ}\] Let me know if you have any questions on how I got those values for B
i understand that makes sence
If B is approximately 13.95477255 degrees, then what is the value of angle C?
is it 180-13.955? if it is then i got 166.045
don't forget about angle A
A+B+C = 180 degrees
156.178
180-13.95477255-9.86666666666667 = 156.178560783333 looks good
If B is approximately 166.045227 degrees, then what is the value of angle C?
i thought b was 13.955
B is two possible angles (we're in the SSA case)
ohhh okay sorry i was confused
eg: sin(30) = 1/2 sin(150) = 1/2 so if you had sin(x) = 1/2 then x = 30 or 150 degrees
oh ok
If B is approximately 166.045227 degrees, then what is the value of angle C?
13.955?
If B is approximately 166.045227 degrees, then what is the value of angle C? C = 180-A-B C = 180-9.86666666666667-166.045227 C = 4.08810633333331
agreed?
yes
So we have 2 possible triangles we can form here Triangle 1 A = 9.86666666666667 degrees B = 13.95477255 degrees C = 156.178560783333 degrees Triangle 2 A = 9.86666666666667 degrees B = 166.045227 degrees C = 4.08810633333331 degrees Angle A stays the same both times all three angles (for either triangle) are approximate
let me know when you're ready for the next part
im ready
For now, let's just focus on Triangle 1 A = 9.86666666666667 degrees B = 13.95477255 degrees C = 156.178560783333 degrees
okay
using these values, are you able to find x in the drawing? |dw:1460075042730:dw|
i think so but im not sure how to
you'll use the law of sines \[\Large \frac{\sin(C)}{c} = \frac{\sin(A)}{a}\] \[\Large \frac{\sin(156.17856^{\circ})}{c} = \frac{\sin( 9.8667^{\circ})}{3761}\] I'll let you solve for c
7301.260
incorrect. Try again
-3549.478
\[\Large \frac{\sin(C)}{c} = \frac{\sin(A)}{a}\] \[\Large \frac{\sin(156.17856^{\circ})}{c} = \frac{\sin( 9.8667^{\circ})}{3761}\] \[\Large 3761*\sin(156.17856^{\circ}) = c*\sin( 9.8667^{\circ})\] \[\Large \frac{3761*\sin(156.17856^{\circ})}{\sin( 9.8667^{\circ})} = c\] \[\Large c = \ ???\]
8864.263
I'm getting 8,864.68360894793
hmm i wonder why
so... Triangle 1 A = 9.86666666666667 degrees B = 13.95477255 degrees C = 156.178560783333 degrees a = 3761 b = 5293 c = 8,864.68360894793
there may be rounding error somewhere
probably
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