Question 1203521
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{{{
drawing(400,400,-4,4,-3,3,
line(-3,2,3,2),line(3,2,1,-2),line(1,-2,-3,2),

line(-3,2,-3,1.7333),line(-3,1.4667,-3,1.2),line(-3,0.9333,-3,0.6667),line(-3,0.4,-3,0.1333),line(-3,-0.1333,-3,-0.4),line(-3,-0.6667,-3,-0.9333),line(-3,-1.2,-3,-1.4667),line(-3,-1.7333,-3,-2),

circle(-3,2,0.05),circle(-3,2,0.07),circle(-3,2,0.09),circle(-3,2,0.11),circle(1,-2,0.05),circle(1,-2,0.07),circle(1,-2,0.09),circle(1,-2,0.11),circle(3,2,0.05),circle(3,2,0.07),circle(3,2,0.09),circle(3,2,0.11),

locate(-3.5+0.1,2.5-0.1,"P"),locate(0.5,-2.5+0.3,"R"),locate(3.5-0.1,2.5-0.1,"Q"),locate(-2.88,1.38,65^o),locate(-2.3,1.8,25^o),locate(-0.78+0.5,2.5,"11"),locate(-1.1,0.56,"7"),locate(1.42+0.1,0.36-0.1,"x"),

locate(2.2,-2.3,matrix(1,2,"Diagram","not")), 
locate(2.2,-2.6,matrix(1,2,"to","scale")) 

)
}}}


PQ = 11
PR = 7
QR = x


Law of cosines
c^2 = a^2 + b^2 - 2ab*cos(C)
x^2 = 7^2 + 11^2 - 2*7*11*cos(25)
x^2 = 30.428600796356
x = sqrt(30.428600796356)
x = 5.5162125408976


The distance from Q to R is about 5.516 km.
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