MACHINE SHOP CALCULATION - OD1640 - LESSON 2/TASK 3
6.
Interpolation
a.
Interpolation is a method of estimating the value of functions of
angles which are not given in the tables, or estimating the angle, given the
function which is not listed in the tables. Briefly, it is a process that
assumes a straight-line difference between two values, such that the sine of
43,, 30' 30" has a value halfway between 43,, 30' and 43,, 31', and may be
found by adding one-half their difference to the function of 43,, 30'
EXAMPLE
Find the sine of 44,, 30' 40".
SOLUTION
Since the sine of 44,, 30' 40" is somewhere between the sine of 44,, 30' and
sine of 44,, 31', find the value of the latter functions and subtract the
value of sin 44,, 30' from the value of sin 44,, 31'.
The desired function is 40/60 or .67 of the one minute difference.
Therefore, .67 x .00021 = .00014
sin 44,, 30' 40" = .70091 + .000014 = .70105.
EXAMPLE
Find the cosine of 43,, 20' 20".
SOLUTION
Find and subtract the value of the function cos 43,, 21' from the value of
the function cos 43,, 20'.
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