A pilot needs to find the distance across a river. From point A, the angle to point B across the river is 40 degrees, and AB along the bank is 50 m. Find the river width:
- 38.30 m, because width = 50 x cos(40) = 50 x 0.766 = 38.30 m, using cosine gives the adjacent side not the opposite
- 32.14 m, because width = 50 x sin(40) = 50 x 0.6428 = 32.14 m, taking the sine of the angle for the width across
- 41.95 m, because width = 50 x tan(40) = 50 x 0.839 = 41.95 m, using tangent with the adjacent bank distance of 50 m
Explanation from PART66Online
The 50 m bank distance is adjacent to the 40 degree angle and the river width is the opposite side, so use tangent: width = adjacent x tan(angle) = 50 x tan(40) = 50 x 0.839 = 41.95 m. Cosine would give the adjacent side, which is the bank length already known, not the width.
E
erik.daros.mac asked · 19h ago
Non si capisce il problema. Il punto B da quale parte della riva è? dalla parte dove devo arrivare o dove sono?
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