MHB How Do You Solve These Trigonometric Identities?

AI Thread Summary
The discussion centers on solving the trigonometric identity (2 - 5cot x) / (2 + 5cot x) = (2sin x - 5cos x) / (2sin x + 5cos x). Participants question the accuracy of the identity and suggest that it should instead be written with cotangent on both sides. Two methods for solving the identity are proposed: multiplying the left side by sin x/sin x or the right side by csc x/csc x. Additionally, the relationships between cotangent, cosecant, sine, and cosine are highlighted as essential for simplifying the expression. The conversation emphasizes the importance of correctly identifying and manipulating trigonometric identities.
fluffertoes
Messages
16
Reaction score
0
How do you do this one? I can't figure it out!
(2 - 5cot x) / (2 + 5cos x) = (2sin x - 5cos x) / (2sin x + 5cos x)
 
Mathematics news on Phys.org
Are you sure you've copied it correctly? It appears to me that the actual identity should be:

$$\frac{2-5\cot(x)}{2+5\cot(x)}=\frac{2\sin(x)-5\cos(x)}{2\sin(x)+5\cos(x)}$$
 
fluffertoes said:
How do you do this one? I can't figure it out!
(2 - 5cot x) / (2 + 5cot x) = (2sin x - 5cos x) / (2sin x + 5cos x)

fixedtwo ways to go

1) multiply left side by sinx/sinx

or

2) multiply right side by cscx/cscx

recall cotx = cosx/sinx and cscx = 1/sinx
 
Thread 'Video on imaginary numbers and some queries'
Hi, I was watching the following video. I found some points confusing. Could you please help me to understand the gaps? Thanks, in advance! Question 1: Around 4:22, the video says the following. So for those mathematicians, negative numbers didn't exist. You could subtract, that is find the difference between two positive quantities, but you couldn't have a negative answer or negative coefficients. Mathematicians were so averse to negative numbers that there was no single quadratic...
Thread 'Unit Circle Double Angle Derivations'
Here I made a terrible mistake of assuming this to be an equilateral triangle and set 2sinx=1 => x=pi/6. Although this did derive the double angle formulas it also led into a terrible mess trying to find all the combinations of sides. I must have been tired and just assumed 6x=180 and 2sinx=1. By that time, I was so mindset that I nearly scolded a person for even saying 90-x. I wonder if this is a case of biased observation that seeks to dis credit me like Jesus of Nazareth since in reality...
Thread 'Imaginary Pythagoras'
I posted this in the Lame Math thread, but it's got me thinking. Is there any validity to this? Or is it really just a mathematical trick? Naively, I see that i2 + plus 12 does equal zero2. But does this have a meaning? I know one can treat the imaginary number line as just another axis like the reals, but does that mean this does represent a triangle in the complex plane with a hypotenuse of length zero? Ibix offered a rendering of the diagram using what I assume is matrix* notation...
Back
Top