#### Introduction into trigonometry

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Introduction into trigonometry

Introduction into trigonometry
Hipparchus Compiled a trigonometric table for
solving triangles.
Today we have all the values saved on computers
: The calculator!
Hipparchus of Rhodes
Born: 190 BC in Nicaea, Bithynia (now Turkey)
Died: 120 BC in probably Rhodes, Greece
Example
Work out the lettered lengths for each of the following right angled triangles,
giving your answers to 1 decimal place:
(i)
14 cm
25°
k
(ii)
a
21 cm
47°
(iii)
63°
b
18 cm
(iv)
21 cm
75°
t
(v)
9°
c
5m
Example
Given triangle ABC below work out the length of BC, giving your answer to
3 significant figures.
C
59°
A
78 mm
B
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?
Example
For the isosceles triangle below, find the length of the third side, giving
your answer correct to 2 decimal places.
10cm
10cm
70°
70°