Which of the following is a challenge when taking a self-portrait?

You can't see the photograph before you take it.
Not having anyone else around
Deciding on the subject of the photograph
All of the above

A, you cant see the photograph before taking it

Explanation:

The answer is quite clear but when shooting a subject that is not you you can make or tell smeone to adjust something and you know how the shot will turn out for the most part. With a self portrait you can see where you will be but geting there and in position is a challange.

coordinates of r(b,c)

slope of nm is 0.

step-by-step explanation:

the midpoint of the line joining the points (x₁,y₁) and (x₂,y₂) is given by

the midpoint of the line segment nk is given by

∴r(b,c)

the slope of the line joining the points (x₁,y₁) and (x₂,y₂) is given by

slope of rs is

hence

coordinates of r(b,c)

and slope of nm is 0.