[br]Sides [i]a[/i] and [i]b [/i]of the above right-angled triangle are called [color=#0000ff]legs (catheta)[/color]. Legs are also the base and the height of the right-angled triangle. The third side is called as [color=#0000ff]hypotenuese[/color]. According to the Pythagoras' theorem,[br][br]         [math]\Large a^2+b^2=c^2[/math][br]  [br][br][color=#3366ff][b]Example 1.[/b][/color] A pole is at right angle to the ground. One end of a guy wire is fixed to the height of 3.2 metres and the other end is 2.6 metres from the pole. How long is the guy wire?[br]

Because the pole is at right angle to the ground, the pole (AC) and the ground (AB) are the legs of the right-angled triangle. By the Pythagoras, [br][br]    [math]\large BC^2=AB^2+AC^2 = 2.6^2+3.2^2=17.0\\[br]\large BC=\sqrt{17.0}\approx 4.1[/math][br][br]The guy wire is about 4.1 metres.