Two corners of a triangle have angles of ( pi )/ 2 π2 and ( pi ) / 6 π6. If one side of the triangle has a length of 4 4, what is the longest possible perimeter of the triangle?

1 Answer
Sep 6, 2016

The longest possible perimeter is 18.928218.9282

Explanation:

As two angles are pi/2π2 and pi/6π6, third angle is

pi-pi/2-pi/6=(6pi)/6-(3pi)/6-pi/6=(2pi)/6=pi/3ππ2π6=6π63π6π6=2π6=π3

Observe that as the angles are 30^o,60^o,90^o30o,60o,90o, the longest side (hypotenuse) is double the smallest side.

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The longest perimeter would be when the side 44 would be opposite smallest angle pi/6π6.

Then longest side of triangle is 2xx4=82×4=8 and third side using Pythagoras theorem is

sqrt(8^2-4^2)=sqrt(64-16)-sqrt48=6.92828242=641648=6.9282

and longest possible perimeter is 4+8+6.9282=18.92824+8+6.9282=18.9282