Respuesta :

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Use Law of Cosines                             g^2 = f^2 + h^2 -2fhCosG                     f^2 = g^2 + h^2 -2ghCosF                    h^2 = f^2 + g^2 -2fgCosH

f^2 = 28^2 + 15^2 -2*28*15Cos87        28^2 = 31^2 + 15^2 -2*31*15CosG 
f^2 = 784 + 225 - 43.96                        784 = 961+225 - 930CosG 
f^2 = 965.0378                                    784 - 1186 = -930CosG
f = 31                                                 -402 = -930CosG             Divide by -930
                                                           .432258 = CosG
                                                           Cos^-1(.432258) = G
                                                             G = 64 degrees

Angle H = 180 - 64 - 87 = 29 degrees

Side f =   31                     Angle F =  87 degrees
Side g =  28                     Angle G = 64 degrees
Side h =  15                     Angle H =29  degrees

Answer:

We have:

  •     f=31 units
  •     m∠G=64°
  •     m∠H=29°

Step-by-step explanation:

We are given angle F as:

m∠GF=87°

Now, g=28 and h=15 we are asked to find f.

Using the law of cosines we have:

[tex]f^2=g^2+h^2-2gh\cos F\\\\f^2=(28)^2+(15)^2-2\times 28\times 15\cos (87)\\\\\\f^2=965.037796\\\\f=31.065[/tex]

which is approximately equal to 31 units

Hence, f=31 units

Also,

[tex]g^2=f^2+h^2-2fh\cos G\\\\\\28^2=15^2+31^2-2\times 15\times 31\times \cos G\\\\\\\cos G=0.4322\\\\G=\arccos 0.4322\\\\\\G=64.392[/tex]

Hence, to the nearest degree we get:

m∠G=64°

Also, we know that the sum of all the angles of a triangle is 180°

Hence,

m∠F+m∠G+m∠H=180°

i.e.

87°+64+m∠H=180°

m∠H=29°

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