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Abel's theorem in problems and solutions - School of Mathematics

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170 Problems <strong>of</strong> Chapter 2<br />

Answer. times.<br />

259. Answer. a) 1; b) 0; c) 1; d) 2.<br />

260. Solution. If <strong>and</strong> are two functions which describe the<br />

cont<strong>in</strong>uous variation <strong>of</strong> the argument along the curves <strong>and</strong> then<br />

as a function describ<strong>in</strong>g the cont<strong>in</strong>uous variation <strong>of</strong> the argument<br />

along C on can take: <strong>in</strong> the case (a) <strong>in</strong> the case (b)<br />

(cf., 226, 239). It follows that<br />

c)<br />

Answer. a) b)<br />

261. H<strong>in</strong>t. (use de Moivre’s formula; cf., 227):<br />

a) (a semi-circle <strong>of</strong> radius<br />

b) (a circle <strong>of</strong> radius<br />

c) (a circle <strong>of</strong> radius twice covered).<br />

262. H<strong>in</strong>t. Use the result <strong>of</strong> Problem 260(a). Answer. a) b)<br />

263. Let be the parametric equation <strong>of</strong> the curve C <strong>and</strong><br />

By hypothesis the variation <strong>of</strong> is equal to The<br />

parametric equation <strong>of</strong> the curve is<br />

The variation <strong>of</strong> the argument <strong>of</strong> is thus equal to (cf., 262(c)).<br />

Hence the curve turns around the po<strong>in</strong>t times. Answer.<br />

times.<br />

264. By hypothesis the variation <strong>of</strong> the argument <strong>of</strong> is equal to<br />

<strong>of</strong> the argument <strong>of</strong> to <strong>of</strong> the argument <strong>of</strong> to<br />

<strong>and</strong> <strong>of</strong> the argument <strong>of</strong> to By the result <strong>of</strong> Problem<br />

260 (a) one obta<strong>in</strong>s:<br />

a) The variation <strong>of</strong> the argument <strong>of</strong><br />

is equal to Answer. The curve turns<br />

around the po<strong>in</strong>t times.<br />

b) Answer. times.<br />

c) Answer. times.<br />

d) Answer.<br />

times.

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