/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q. 87 Explain why the following test f... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Explain why the following test for symmetry is valid: Replace r by -r and θby-θin a polar equation. If an equivalent

equation results, the graph is symmetric with respect to the

line θ=π2(y-axis).

(a) Show that the test on page 574 fails for r2=cosθ, yet this new test works.

(b) Show that the test on page 574 works for r2=sinθ, yet

this new test fails.

Short Answer

Expert verified

(a) Assuring all the conditions the new test works.

(b) Assuring all the conditions the new test does not works.

Step by step solution

01

Part (a) Step 1. Given 

Given polar coordinate

r2=cosθ

02

Step 2. Explanation

Consider

r2=cosθ

Now, by symmetry test with respect to polar coordinate

replace localid="1646736860762" θ·É¾±³Ù³óÏ€-θ

therefore,

r2=cosÏ€-θ=-³¦´Ç²õθ

the two are not equivalent therefore test fails.

Now replace r with -r and

θwith-θtherefore,(-r)2=cos(-θ)r2=³¦´Ç²õθ

hence the new test works.

03

Part (b) Step 1. Given

Given polar coordinate

r2=sinθ

04

Part (b) Step 2. Explanation

Consider,

r2=sinθreplaceθwithÏ€-θthus,r2=sinÏ€-θ=²õ¾±²ÔθthustwoareequalhencetestworksNowreplacerwith-randθwith-θ(-r)2=sin(-θ)r2=-²õ¾±²ÔθThetwoarenotequalsotestfails.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Study anywhere. Anytime. Across all devices.