Qwertyuiop[]
Junior Member
- Joined
- Jun 1, 2022
- Messages
- 123
Hi, I have to find the modulus and the arg of this complex number: [math]\frac{1}{1+i \ tan \theta }[/math]I started by writing this in the general/algebraic form.
After multiplying the numerator and denominator with conjugate and simplifying i get: [math]cos^2\theta \:-\:i\:sin\theta cos\theta[/math]Then [math]a=cos^2\theta \:\\ b=-sin\theta cos\theta[/math]So the modulus is [math]\sqrt{\left(cos^2\theta \right)^2+\left(cos\theta sin\theta \right)^2}[/math] which simplifies to [math]cos\:\theta[/math]
To find the argument of z, we learned this formula [imath]cos\:\theta \:=\:\frac{a}{\left|z\right|}\:;\:sin\:\theta \:=\:\frac{b}{\left|z\right|}\:\:[/imath]
using this i get : [imath]cos\:\theta \:=\:cos\:\theta \:\:\:\:and\:sin\:\theta \:=-\:sin\:\theta[/imath]
cos theta is positive and sin theta is negative therefore it must be in the 4 quadrant so i wrote arg(z) as an inequality [math]0\:\le arg\left(z\right)\le -\frac{\pi }{2}[/math]Is the answer for mod(z) and arg(z) correct?
After multiplying the numerator and denominator with conjugate and simplifying i get: [math]cos^2\theta \:-\:i\:sin\theta cos\theta[/math]Then [math]a=cos^2\theta \:\\ b=-sin\theta cos\theta[/math]So the modulus is [math]\sqrt{\left(cos^2\theta \right)^2+\left(cos\theta sin\theta \right)^2}[/math] which simplifies to [math]cos\:\theta[/math]
To find the argument of z, we learned this formula [imath]cos\:\theta \:=\:\frac{a}{\left|z\right|}\:;\:sin\:\theta \:=\:\frac{b}{\left|z\right|}\:\:[/imath]
using this i get : [imath]cos\:\theta \:=\:cos\:\theta \:\:\:\:and\:sin\:\theta \:=-\:sin\:\theta[/imath]
cos theta is positive and sin theta is negative therefore it must be in the 4 quadrant so i wrote arg(z) as an inequality [math]0\:\le arg\left(z\right)\le -\frac{\pi }{2}[/math]Is the answer for mod(z) and arg(z) correct?