You don't!
Boats use them to navigate.
cause they are important
You do not have to. You could use polar coordinates, if you prefer.
If by sperical triangle you mean a triangle on the surface of a sphere, you will need 3 dimensional coordinate geometry. Whether you use polar coordinates or linear coordinates will depend on what you want to "solve".
how to use number line to represent real life event
Boats use them to navigate.
cause they are important
Polar coridniates
You do not have to. You could use polar coordinates, if you prefer.
I will assume a vector in a plane - in two dimensions. The idea of polar coordinates is that the vector is expressed as its length, and an angle. If you already have the vector in rectangular coordinates, i.e. the x and y components, most scientific calculators have a function that might be labelled R->P, to convert from rectangular coordinates to polar coordinates. Otherwise, use basic trigonometry - but using the specialized function is much faster, if your calculator has it.
True
You can use a scientific calculator to convert from polar coordinates (length and direction) to rectangular coordinates (x-coordinate and y-coordinate). Most calculators have such a function directly; it is much easier to use this, than to use the special trigonometric formulae. Then, add the x- and y-components separate. You may want to convert the end-result back to polar coordinates - once again, use the special functions on your calculator, in this case, rectangular-to-polar conversion.
If by sperical triangle you mean a triangle on the surface of a sphere, you will need 3 dimensional coordinate geometry. Whether you use polar coordinates or linear coordinates will depend on what you want to "solve".
To add two vectors, you add the components. The angles are specified in polar coordinates (magnitude and angle); use the same convention for both angles (for example, measure them from the x-axis counterclockwise), then use your scientific calculator to convert from polar coordinates to rectangular coordinates. Most scientific calculators have a P->R conversion. After that, you can add the components of the vectors separately. Since you want the magnitude and direction of the resultant force, you then need to convert back to polar coordinates (R->P conversion, on your calculator).
cartesian coordinates can be used in measuring distance and direction in relation to a systems to rigid bodies. you could also use cartesian while graphing. also u could use it when you're selling. The best example of coordinates in everyday life is use of longitude and latitude on globe. Each unique location on the earth has a unique combination of longitude and latitude. Global positioning system used by radio taxi operators also uses x,y coordinates to find exact location of a vehicle.
how to use number line to represent real life event
School is part of real life... if you are using equations in school that is real.