Page 45 - Trigonometry

Example 13
A linear function intercepts a cos(αx) function at the

following coordinates,

(−3.1, − 0.647), (−1.18, 0.047), (0.622, 0.692)

Determine the gradient and y-axis intercept and the

value of α.

Let the linear function be,

= +

Need to find the values α, b and c. From the first

coordinate,

−0.674 = −3.1 +

or,

3.1 − = 0.674 1

From the second coordinate,

0.047 = − 1.18 +

or

1.18 − = −0.047 2

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