Elements of Plane and Spherical Trigonometry

C.W. Crockett, American Book Co.,  1896.

Trig like you haven't seen it before!! This is a trig circle - it is how trig functions used to be visualized. The radius is equal to one and the lengths of the lines are equal to the values of the trig functions they are labeled with. Note the presence of the versed sin (versθ = 1-cosθ) and coversed sin (coversθ = 1- sinθ) functions. The suversed sin function (suversθ = 1+cosθ) is not shown.

If AD = a, can you find the expression for CB, the height of the tower in terms of a, α and β?

A ship sailed from D to C. The lighthouse is 200' tall. If  γ = 10^o14.3' , γ' = 11^o10.6' and the angle shown at the base of the lighthouse is 127^o14.4' can you find the distance DC?

Wow! Can you find the height h of the tower in terms of a, b, α, β and γ?

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