Post on 02-Jan-2016
Introduction into trigonometry
Born: 190 BC in Nicaea, Bithynia (now Turkey)Died: 120 BC in probably Rhodes, Greece
Hipparchus of RhodesHipparchus Compiled a trigonometric table for solving triangles. Today we have all the values saved on computers : The calculator!
Example
Work out the lettered lengths for each of the following right angled triangles,
giving your answers to 1 decimal place:
(i)
25°
14 cm
k
47°
21 cma
(ii)
63°
18 cm
b
(iii)
75°21 cm
t
(iv)
9°
5 m
c
(v)
ExampleGiven triangle ABC below work out the length of BC, giving your answer to 3 significant figures.
A B
C
78 mm
59°
Example
A piece of gutter pipe is 350cm long is angled at 6° to the horizontal.
How much higher is the upper end of the guttering than its lower end?
Example
When a set of ladders of length 13m are placed against a vertical wall they
make an angle of 68° with the horizontal.
How far up the wall does the ladder reach?
10cm 10cm
70° 70°
ExampleFor the isosceles triangle below, find the length of the third side, giving your answer correct to 2 decimal places.