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avatar+97 

 

so: 

Cos(x) = 7^2 + 10^2 - 10^2/2(7 * 10)

cos(x) = 49/140

acos(0.35) = x

x= 69.5 degrees.

 

Let me know if this looks good for explaining my answer! 

Thanks

 Feb 14, 2019
 #1
avatar+100516 
+1

You kinda' have the right idea, StarStrike

 

Note...BA = CA  = 10 m

 

The Law of Cosines says that

 

BC^2 =  BA^2 + CA^2 -  2(BA)(CA) cos (x)       .....so we have...

 

7^2 = 10^2 + 10^2 - 2(10)(10) cos (x)        simplify

 

49 =  200 - 200 cos(x)       subtract 200 from both sides

 

[ 49 - 200] = - 200 cos(x)     divide both sides by - 200

 

[ 49 - 200 ] / -200    =  cos (x)

 

To find the measure of x, use the arccos   (inverse cosine)...make sure you are in "degree" mode...so we have

 

arccos  [ ( 49 - 200) / -200 ]  =  x =  40.97° 

 

 

cool cool cool

 Feb 14, 2019
 #2
avatar+97 
+1

I thought it looked a bit off.

Thanks CPhill!smiley

StarStrike  Feb 14, 2019
 #3
avatar+100516 
0

OK....hang in there, StarStrike.....this will begin to make sense in a bit.....

 

 

 

cool cool cool

CPhill  Feb 14, 2019

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