## An Elementary Treatise on Plane Trigonometry |

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acute angle angle subtended angle whose cosine angle whose sine angles OA Article centre CHAPTER circular measure circum-circle circumference co-ratio cos A cos cos2 cos3 cos4 cosec cosine cot2 cotangent decimal diff elevation equal escribed EXAMPLES Express Find the angle Find the height Find the number find the values formulae hence horizontal plane inches inscribed circle Inverse Functions L sin logarithms middle point nearly negative nine-point circle number of degrees number of grades observed pedal triangle perpendicular polygon positive projection Prove the following quadrant quadrilateral radians radii sec2 set of angles sexagesimal sin A sin sin2 sin3 sin4 sine sine and cosine Solve the equations subtends an angle tabular difference tan2 tangent tower triangle ABC trigono trigonometrical ratios vertical yards Zsin

### Popular passages

Page 52 - From the top of a tower, whose height is 108 feet, the angles of depression of the top and bottom of a vertical column standing in the horizontal plane are found to be 30° and 60° respectively ; required the height of the column.

Page 206 - The angular elevation of a tower at a place A due south of it is 30° ; and at a place B due west of A, and at a distance a from it, the elevation is 18°...

Page 196 - A person standing on the bank of a river observes the elevation of the top of a tree on the opposite bank to be 51°...

Page 219 - The three perpendiculars from the vertices of a triangle to the opposite sides (produced if necessary) are called the altitudes...

Page 287 - In any triangle, the sides are proportional to the sines of the opposite angles. That is, sin A = sin B...

Page 111 - C = 1 + 4 sin £A sin £B sin £C. 37. tan A + tan B + tan C = tan A tan B tan C.

Page 201 - A lighthouse facing N. sends out a fan-shaped beam extending from NE to NW A steamer sailing due W. first sees the light when 5 miles away from the lighthouse and continues to see it for 30^/2 minutes. What is the speed of the steamer 1 5.