# An elementary treatise on plane trigonometry [&c.].

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Page 30 - The sum of two sides of a triangle is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference
Page 42 - Logarithm.—The logarithm of a number is the exponent of the power to which a given base must be raised
Page 17 - and the Cosine of the Difference of two Angles, in terms of the Sines and Cosines of the Angles themselves. Let the
Page 47 - Two observers on the same side of a balloon, and in the same vertical plane with it, a mile apart, find its angles of elevation to be
Page 18 - Cosine of the Sum of two Angles in terms of the Sines and Cosines of the Angles themselves. Let the
Page 23 - The sum of the sines of any two angles is equal to twice the sine of half their sum multiplied by the cosine of half their difference.
Page 23 - The difference of the sines of any two angles is equal to twice the cosine of half their sum multiplied by the sine of half their difference.
Page vi - and cosine of the sum of two angles in terms of the sines and cosines of the angles themselves,
Page vi - and cosine of the difference of two angles, in terms of the sines and cosines of the angles themselves,
Page 1 - angle subtended at the centre of a circle by an arc of the circumference, equal in length to the radius