SOLUTION: Solve the triangle using Law of sines or cosines. A=42(angle A) b=120 (side b) c=160 (side c)

Keep all decimals until the end, then round.


°

Make sure your calculator is in DEGREE mode
and not RADIAN mode.

Punch that in your calculator and you get:



Then taking square roots of both sides



Now we use the law of sines:



We need only the first two parts:



cross-multiply:



Divide both sides by a



Substitute:



Calculate



No use the inverse sine key 
on your calculator

°

Now we find angle C from

°







°
  
So the three missing parts are


°
°

But using the rounding rules, the angles
should be rounded to the nearest degree just 
like the given angle 42°, and the side should
be rounded to the nearest two significant 
digits.  So using the rounding rules:

  (side a)
°  (Angle B) 
°  (Angle C)

Edwin