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TRIGONOMETRIC TABLES
– Trigonometric tables deals with readings of the value of angles of sine, cosine and tangent from mathematical table when they are already prepared into four decimal
HOW TO READ THE VALUE OF TRIGONOMETRIC ANGLES FROM MATHEMATICAL TABLES
Example 1
Find the value of the following by using mathematical table
(i) Sin 43°= 0.6820
(ii) Sin 58º = 0.8480
(iii) Sin 24°42′ = 0.4179
(iv) Sin 52°26′ = 0.7923 + 4 = 0.7927
Example 2
By using mathematical tables evaluate the following
(a)Cos 37° =0.7986
(b)Cos82° =0.1392
(c)Cos 71°34′ =0.3162
(d)Tan 20° = 0.3640
(e)Tan 68° =2.4751
(f)Tan 54°22′ = 1.3950
Example3.
Find the value of the following letter from trigonometric rations
(i) Sin p = 0.6820
Sin p = 0.6820
P = Sin-1 (0.6820)
P = 43°
ii) Sin Q = 0.7291
Q = Sin-1 (0.7291)
Q = 46°48’
iii) Tan R = 5.42°45
R = 5. 42°45
R = tan-1 (5.42°45)
R = 79°33
APPLICATION OF SINE, COSINE AND TANGENT RATIOS IN SOLVING A TRIANGLE
Sine, cosine and triangle of angles are used to solve the length of unknown sides of triangles
Example
From
SO | TO | CA |
H | A | H |
Sine C = 
Sin 55Ëš= 
20 x Sin 55Ëš= x
20 x 0.8198 = x
x = 16.4 cm
The value of x = 16.4cm
Example 2
Find the length XY in a XYZ
Solution:
From
SO | TO | CA |
H | A | H |
tan 62Ëš = 
tan 62° = 
13 x tan 62° = xy
13 x 1.8807 = xy
24.4cm = xy
xy = 24.4cm
Example
Evaluate the value of m and give your answer into 3 decimal places
From
SO | TO | CA |
H | A | H |
Cos R =
Cos 36° = 
m = 
m = 
m = 14.833 cm
The value of m is 14.833 cm
EXERCISE
Solution:
From
SO | TO | CA |
A | H |
tan 43° = 
tan 43°=
17 x tan 43° = y
y = 17 
y =15.85cm
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