Question

Given tanØ =4/3 and sin(-4/5) find cosØ
A. 1/3
B. - 1/3
C. 3/5
D. - 3/5
E. -√3/5

Answer 1

if cosØ = -3/5 and sinØ < 0
find tanØ (nearest fourth decimal digit)
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If cos and sin are both negative theta is in QIII.
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Since cos = x/r = -3/5, x = -3 and r = 5
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Solve for "y":



y = sqrt[r^2 - x^2] = sqrt[25-9] = sqrt(16) = 4
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But y is negative in QIII, so y = -4
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Tan is positive in QIII:
tan(theta) = y/x = -4/-3 = 4/3

Answer 2

thats a dif question but im showing u how to work a problem like that

Answer 3

could you give an example where the value of sin isn't 0 so i can compare them easier

Answer 4

i follow you up until "solve for y"

Answer 5

question seems a little off

Answer 6

Did you mean:
"Given tan(Ø)=4/3 and sin(Ø)=-4/5 find cos(Ø)"

Answer 7

here u go freckles

Answer 8

wow they made a huge type-o then

Answer 9

ive found so many errors in the basic math on plato it worrys me when i get to the harder stuff like this, especially when others see the mistakes too :(

Answer 10

I bet you they meant to write
"Given tan(Ø)=4/3 and sin(Ø)=-4/5 find cos(Ø)"

Answer 11

it shouldn't say sin(-4/5)
this tells us nothing

Answer 12

well in that case can you help me solve that problem and ill put the answer to that in?

Answer 13

\[\tan(\theta)=\frac{\sin(\theta)}{\cos(\theta)}\]

use this

Answer 14

replace tan(theta) with 4/3
and replace sin(theta) with -4/5
and solve for cos(theta)

Answer 15

if you want you can replace cos(theta) with u
if that makes things easier to see and helps you solve

Answer 16

soooooo -3/5?

Answer 17

\[\frac{4}{3}=\frac{\frac{-4}{5}}{u} \\ \frac{4}{3}=\frac{-4}{5 u} \\ \\ \text{ cross multiply } \\ 20u=-12 \\ u=\frac{-12}{20}=\frac{-3}{5}\]
yep

Answer 18

but seriously I hope you see why the sin(-4/5) is a type-o

Answer 19

thank you so much, and i do thats why the first answer seemed confusing. its sad that plato isnt formatted correctly though :/

Answer 20

very sad

Answer 21

you would think tons of people would have looked it over

Answer 22

and corrected the software

Answer 23

especially when we are expected to only use the knowledge given to us by plato, asking for help like i did is considered "cheating" lol