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A portion of a power line support tower is to be constructed as congruent triangles, as shown on the diagram. The crossing beams will be 11m long and will intersect at an acute angle of 50 degrees, and angle S= 37 degrees. Find the lengths of all sides of the triangle QPT

 

 

https://gyazo.com/320d833e95efb64d446cd9b6277441ff        -diagram

 Jul 20, 2019

Best Answer 

 #1
avatar+9488 
+5

 

By the SAS congruence theorem,  △PQT ≅ △SRT  So...

 

m∠QPT  =  m∠RST  =  37°

 

m∠QTP  =  180° - 50°   =   130°

 

m∠PQT  =  180° - 37° - 130°  =  13°

 

Since  QT = RT  we can substitute  QT  in for  RT in the next equation.


RT+TP = 11 QT+TP = 11 QT = 11TP

 

Now we can substitute  11 - TP  in for  QT in the next equation.

 

By the Law of Sines,

 

TPsin13 = QTsin37 TPsin37sin13 = QT TPsin37sin13 = 11TP TPsin37sin13+TP = 11 TP(sin37sin13+1) = 11 TP = 11÷(sin37sin13+1) TP = 11sin13sin37+sin13

 

Now that we know the length of  TP ,  we can find the length of  QT.

 

QT = 11TP QT = 1111sin13sin37+sin13

 

Finally, we can use the Law of Sines again to find  QP.

 

QPsin130 = TPsin13 QP = TPsin130sin13 QP = 11sin13sin37+sin13sin130sin13 QP = 11sin130sin37+sin13

 

So we have found:

 

TP=11sin13sin37+sin132.993 QT=1111sin13sin37+sin138.007 QP=11sin130sin37+sin1310.192

 

And all lengths are in meters.

 Jul 20, 2019
 #1
avatar+9488 
+5
Best Answer

 

By the SAS congruence theorem,  △PQT ≅ △SRT  So...

 

m∠QPT  =  m∠RST  =  37°

 

m∠QTP  =  180° - 50°   =   130°

 

m∠PQT  =  180° - 37° - 130°  =  13°

 

Since  QT = RT  we can substitute  QT  in for  RT in the next equation.


RT+TP = 11 QT+TP = 11 QT = 11TP

 

Now we can substitute  11 - TP  in for  QT in the next equation.

 

By the Law of Sines,

 

TPsin13 = QTsin37 TPsin37sin13 = QT TPsin37sin13 = 11TP TPsin37sin13+TP = 11 TP(sin37sin13+1) = 11 TP = 11÷(sin37sin13+1) TP = 11sin13sin37+sin13

 

Now that we know the length of  TP ,  we can find the length of  QT.

 

QT = 11TP QT = 1111sin13sin37+sin13

 

Finally, we can use the Law of Sines again to find  QP.

 

QPsin130 = TPsin13 QP = TPsin130sin13 QP = 11sin13sin37+sin13sin130sin13 QP = 11sin130sin37+sin13

 

So we have found:

 

TP=11sin13sin37+sin132.993 QT=1111sin13sin37+sin138.007 QP=11sin130sin37+sin1310.192

 

And all lengths are in meters.

hectictar Jul 20, 2019

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