Hi Maria,
I am going to give you suggestions for two of the problems
2. Calculate the greatest interior angle (correct to three decimal places) in a triangle having
edge lengths of 10; 15 and 20 metres.
Draw a reasonably accurate diagram of a triangle with side length 10, 15 and 20 centimeters. Which of the three interior angles is the largest? Use the Law of Cosines to find its measure.
4. The position of two airplanes, A and B, is recorded by a radar station. The airplanes are
both equidistant from the radar station and the rays to their respective positions from
the radar station form an angle of $\frac{\pi}{4}$ radians (at the radar station). If the airplanes are
80 km apart, what distance is airplane A from the radar station (correct to three decimal
places)?
Again draw a diagram. The triangle formed by A, B and the radar station is an isosceles, right triangle. Pythagoras theorem should help at this point.
Penny
