Trig indenties

[Ramulala]

Question: If cot(X) = 8/21 in quadrant-1, find sin (2x) =

What I did
Cot(X) = 8/21 = tan (X) = 21/8

I attached my work and I got 336/505 = 0.66547712

The question is asking me to give answers in decimal places!

I don't know what wrong I'm doing!

 

[jonah2.0]

Beer soaked opinion follows.

Question: If cot(X) = 8/21 in quadrant-1, find sin (2x) =

What I did
Cot(X) = 8/21 = tan (X) = 21/8

I attached my work and I got 336/505 = 0.66547712

The question is asking me to give answers in decimal places!

I don't know what wrong I'm doing!

`sin2x=2*sinx*cosx`

Also, `336/505=.6\overline{6534}`

336/505 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

 

[Ramulala]

I don't know why is this wrong????

 

[Deleted member 4993]

I don't know why is this wrong????

you used wrong identity for sin(2x)

it should be

sin(2x) = 2 * sin(x) * cos(x)​

 

[Ramulala]

What? I think it's right.
Sin2x = 2 * 8/√505 * 21/√505 =

Is this the correct form?

 

[Deleted member 4993]

What? I think it's right.
Sin2x = 2 * 8/√505 * 21/√505 =

Is this the correct form? Yes

According to your previous calculations (response #2)

sin(x) = 21/(√505)

cos(x) = 8/(√505)

sin(2x) = 2*sin(x)*cos(x) = 2 * 21/(√505) * 8/(√505) = 336/505 = 0.6653

But in your hand written response (Response #2)

You wrote (3rd line from the bottom) the wrong expression for sin(2x).

 

[Ramulala]

Got it! The answer was .6653
The computer was not taking 0.6653 as a answer

 

[jonah2.0]

Beer soaked comment follows.

Got it! The answer was .6653
The computer was not taking 0.6653 as a answer

The computer must be broken.

 

[Steven G]

Why are you writing that the angle is x yet in your triangle you wrote that the angle is [math]\theta[/math]?