91Ó°ÊÓ

The given expression is cos(ix).

The domain of a function refers to the range of values that can be plugged into it. This is the set x of values in a function like f (x). The range of a function is the set of values that the function can take. This is the set of values that the function produces when we enter x value. The y values are what you're looking for.

The basic hyperbolic functions are:

1. Hyperbolic sine(sinh)
2. Hyperbolic cosine(cosh)
3. Hyperbolic tangent(tanh)

Let, cos(ix)=cos(iz).

Use the formula mentioned below.

sin(iz)=isinh(z)

tan(iz)=itanh(z)

Divide Left Hand Side of first identity by second identity.

$\frac{\sin \left(\mathrm{iz}\right)}{\tan \left(\mathrm{iz}\right)}=\cos \left(\mathrm{iz}\right)$ …. (1)

Divide Left Hand Side of first identity by second identity.

role="math" localid="1658812611018" $\frac{\mathrm{i}\sinh \left(\mathrm{iz}\right)}{\mathrm{i}\tanh \left(\mathrm{iz}\right)}=\cos h\left(z\right)$ …. (2)

Combine equation (1) and equation (2).

cos(iz)=cosh(z)

cos(ix)=cosh(x)

Hence,

The Real part of cos(ix) is cos(x) .

The Imaginary part of cos(ix) is 0.

The absolute value of cos(ix) is |cos(ix)|=cos(x) .