Calculus 2 : Polar Form

Study concepts, example questions & explanations for Calculus 2

varsity tutors app store varsity tutors android store

Example Questions

Example Question #51 : Polar Form

What is the polar form of \(\displaystyle y=6x-11\)?

Possible Answers:

\(\displaystyle r=-\frac{11}{6\sin\theta-\cos \theta}\)

\(\displaystyle r=-\frac{11}{\sin\theta-6\cos \theta}\)

\(\displaystyle r=-\frac{11}{\sin\theta+6\cos \theta}\)

\(\displaystyle r=\frac{11}{\sin\theta+6\cos \theta}\)

\(\displaystyle r=\frac{11}{\sin\theta-6\cos \theta}\)

Correct answer:

\(\displaystyle r=-\frac{11}{\sin\theta-6\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=6x-11\), then:

\(\displaystyle r\sin\theta=6r\cos \theta-11\)

\(\displaystyle r\sin\theta-6r\cos \theta=-11\)

\(\displaystyle r(\sin\theta-6\cos \theta)=-11\)

\(\displaystyle r=-\frac{11}{\sin\theta-6\cos \theta}\)

 

Example Question #52 : Polar Form

What is the polar form of \(\displaystyle y=\frac{1}{2}-x\)?

Possible Answers:

\(\displaystyle r=-\frac{3}{4(\sin\theta-\cos \theta)}\)

\(\displaystyle r=\frac{3}{4(\sin\theta-\cos \theta)}\)

\(\displaystyle r=\frac{3}{\sin\theta+4\cos \theta}\)

\(\displaystyle r=-\frac{3}{4(\sin\theta+\cos \theta)}\)

\(\displaystyle r=\frac{1}{2(\sin\theta+\cos \theta)}\)

Correct answer:

\(\displaystyle r=\frac{1}{2(\sin\theta+\cos \theta)}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and .

Given

 \(\displaystyle y=\frac{1}{2}-x\), then:

\(\displaystyle r\sin\theta=\frac{1}{2}-r\cos \theta\)

\(\displaystyle r\sin\theta+r\cos \theta=\frac{1}{2}\)

\(\displaystyle r(\sin\theta+\cos \theta)=\frac{1}{2}\)

\(\displaystyle r=\frac{1}{2(\sin\theta+\cos \theta)}\)

Example Question #221 : Parametric, Polar, And Vector

What is the polar form of \(\displaystyle y=\frac{3}{9}x^{2}\)?

Possible Answers:

\(\displaystyle r=\frac{1}{3}\tan \theta\sec\theta\)

\(\displaystyle r=\tan \frac{1}{3}\theta\sec\theta\)

\(\displaystyle r=3\tan \theta\sec\theta\)

\(\displaystyle r=-3\tan \theta\sec\theta\)

\(\displaystyle r=-\frac{1}{3}\tan \theta\sec\theta\)

Correct answer:

\(\displaystyle r=3\tan \theta\sec\theta\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=\frac{3}{9}x^{2}\), then:

\(\displaystyle r\sin\theta=\frac{3}9{}(r\cos \theta)^{2}\)

\(\displaystyle r\sin\theta=\frac{3}{9}r^{2}\cos^{2} \theta\)

Dividing both sides by , we get:

\(\displaystyle \tan \theta=\frac{3}9{}r\cos\theta\)

\(\displaystyle \frac{\tan \theta}{\cos\theta}=\frac{3}{9}r\)

\(\displaystyle \tan \theta\sec\theta=\frac{3}{9}r\)

\(\displaystyle r=\frac{9}{3}\tan \theta\sec\theta\)

\(\displaystyle r=3\tan \theta\sec\theta\)

Example Question #53 : Polar Form

What is the polar form of \(\displaystyle y=5x+14\)?

Possible Answers:

None of the above

\(\displaystyle r=-\frac{14}{\sin\theta+5\cos \theta}\)

\(\displaystyle r=-\frac{14}{\sin\theta-5\cos \theta}\)

\(\displaystyle r=\frac{14}{\sin\theta-5\cos \theta}\)

\(\displaystyle r=\frac{14}{\sin\theta+5\cos \theta}\)

Correct answer:

\(\displaystyle r=\frac{14}{\sin\theta-5\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=5x+14\), then:

\(\displaystyle r\sin\theta=5r\cos \theta+14\)

\(\displaystyle r\sin\theta-5r\cos \theta=14\)

\(\displaystyle r(\sin\theta-5\cos \theta)=14\)

\(\displaystyle r=\frac{14}{\sin\theta-5\cos \theta}\)

Example Question #51 : Polar

What is the polar form of \(\displaystyle y=x-12\)?

Possible Answers:

None of the above

\(\displaystyle r=-\frac{12}{\sin\theta-\cos \theta}\)

\(\displaystyle r=\frac{12}{\sin\theta-\cos \theta}\)

\(\displaystyle r=\frac{12}{\sin\theta+\cos \theta}\)

\(\displaystyle r=-\frac{12}{\sin\theta+\cos \theta}\)

Correct answer:

\(\displaystyle r=-\frac{12}{\sin\theta-\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=x-12\), then:

\(\displaystyle r\sin\theta=r\cos \theta-12\)

\(\displaystyle r\sin\theta-r\cos \theta=-12\)

\(\displaystyle r(\sin\theta-\cos \theta)=-12\)

\(\displaystyle r=-\frac{12}{\sin\theta-\cos \theta}\)

 

Example Question #61 : Polar

What is the polar form of \(\displaystyle y=9x-8\)?

Possible Answers:

\(\displaystyle r=\frac{8}{\sin\theta-9\cos \theta}\)

\(\displaystyle r=-\frac{8}{\sin\theta-9\cos \theta}\)

\(\displaystyle r=-\frac{8}{9\sin\theta-\cos \theta}\)

\(\displaystyle r=-\frac{8}{\sin\theta+9\cos \theta}\)

\(\displaystyle r=\frac{8}{\sin\theta+9\cos \theta}\)

Correct answer:

\(\displaystyle r=-\frac{8}{\sin\theta-9\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=9x-8\), then:

\(\displaystyle r\sin\theta=9(r\cos \theta)-8\)

\(\displaystyle r\sin\theta-9(r\cos \theta)=-8\)

\(\displaystyle r(\sin\theta-9\cos \theta)=-8\)

\(\displaystyle r=-\frac{8}{\sin\theta-9\cos \theta}\)

 

 

 

 

Example Question #62 : Polar

What is the polar form of \(\displaystyle y=7+x\)?

Possible Answers:

\(\displaystyle r=-\frac{7}{\sin\theta+\cos \theta}\)

\(\displaystyle r=-\frac{7}{\sin\theta-\cos \theta}\)

\(\displaystyle r=\frac{7}{\sin\theta+7\cos \theta}\)

\(\displaystyle r=\frac{7}{\sin\theta-\cos \theta}\)

\(\displaystyle r=\frac{7}{\sin\theta+\cos \theta}\)

Correct answer:

\(\displaystyle r=\frac{7}{\sin\theta-\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and .

Given \(\displaystyle y=7+x\), then:

\(\displaystyle r\sin\theta=7+r\cos \theta\)

\(\displaystyle r\sin\theta-r\cos \theta=7\)

\(\displaystyle r(\sin\theta-\cos \theta)=7\)

\(\displaystyle r=\frac{7}{\sin\theta-\cos \theta}\)

 

Example Question #63 : Polar

What is the polar form of \(\displaystyle y=\frac{5}{11}x^{2}\)?

Possible Answers:

\(\displaystyle r=\tan\frac{11}{5}\theta\sec\theta\)

\(\displaystyle r=\frac{11}{5}\tan\theta\sec\theta\)

\(\displaystyle r=-\frac{5}{11}\tan\theta\sec\theta\)

\(\displaystyle r=\frac{5}{11}\tan\theta\sec\theta\)

\(\displaystyle r=-\frac{11}{5}\tan\theta\sec\theta\)

Correct answer:

\(\displaystyle r=\frac{11}{5}\tan\theta\sec\theta\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities:  and .

Given \(\displaystyle y=\frac{5}{11}x^{2}\), then:

\(\displaystyle r\sin\theta=\frac{5}{11}(r\cos \theta)^{2}\)

\(\displaystyle \tan\theta=\frac{5}{11}(r\cos \theta)\)

\(\displaystyle r=\frac{11}{5}(\frac{\tan\theta}{\cos\theta})\)

\(\displaystyle r=\frac{11}{5}\tan\theta\sec\theta\)

 

Example Question #64 : Polar

What is the polar form of \(\displaystyle y=\frac{6}{5}x^{2}\)?

Possible Answers:

\(\displaystyle r=\tan\frac{5}{6} \theta\sec\theta\)

\(\displaystyle r=-\frac{5}{6}\tan \theta\sec\theta\)

\(\displaystyle r=\frac{6}{5}\tan \theta\sec\theta\)

\(\displaystyle r=-\frac{6}{5}\tan \theta\sec\theta\)

\(\displaystyle r=\frac{5}{6}\tan \theta\sec\theta\)

Correct answer:

\(\displaystyle r=\frac{5}{6}\tan \theta\sec\theta\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=\frac{6}{5}x^{2}\), then:

\(\displaystyle r\sin\theta=\frac{6}{5}(r\cos \theta)^{2}\)

\(\displaystyle r\sin\theta=\frac{6}{5}r^{2}\cos^{2} \theta\)

Dividing both sides by , we get:

\(\displaystyle \frac{\tan \theta}{\cos\theta}=\frac{6}{5}r\)

\(\displaystyle \tan \theta\sec\theta=\frac{6}{5}r\)

\(\displaystyle r=\frac{5}{6}\tan \theta\sec\theta\)

Example Question #64 : Polar

What is the polar form of \(\displaystyle y=6x-5\)?

Possible Answers:

\(\displaystyle r=-\frac{5}{6\sin\theta-\cos \theta}\)

\(\displaystyle r=\frac{5}{\sin\theta-6\cos \theta}\)

\(\displaystyle r=\frac{5}{\sin\theta+6\cos \theta}\)

\(\displaystyle r=-\frac{5}{\sin\theta-6\cos \theta}\)

\(\displaystyle r=-\frac{5}{\sin\theta+6\cos \theta}\)

Correct answer:

\(\displaystyle r=-\frac{5}{\sin\theta-6\cos \theta}\)

Explanation:

We can convert from rectangular to polar form by using the following trigonometric identities: and . Given \(\displaystyle y=6x-5\), then:

\(\displaystyle r\sin\theta=6(r\cos \theta)-5\)

\(\displaystyle r\sin\theta-6(r\cos \theta)=-5\)

\(\displaystyle r(\sin\theta-6\cos \theta)=-5\)

\(\displaystyle r=-\frac{5}{\sin\theta-6\cos \theta}\)

Learning Tools by Varsity Tutors