The answer will depend on linear WHAT!
halala
Depends if you enjoy Linear Equations or Trigonometry more. :)
Scatter graphs are best. Line graphs are OK if the trend is linear but not much good if the trend is non-linear.
Depends on your definition of "linear" For someone taking basic math - algebra, trigonometry, etc - yes. Linear means "on the same line." For a statistician/econometrician? No. "Linear" has nothing to do with lines. A "linear" model means that the terms of the model are additive. The "general linear model" has a probability density as a solution set, not a line...
plane trigonometry spherical trigonometry
The main kinds are plane trigonometry and solid trigonometry. The latter will include trigonometry in hyper-spaces.
Well the short answer I know of, is that through the use of linear algebra operations, (which define trigonometry), 3D models can be manipulated very easily. All of the points on a 3D display are run though a matrix multiplication operation that to the effect of multiplying each point by the cos(x).
Hipparchus is the father of trigonometry.
TRIGONOMETRY
It is a number - in trigonometry or elsewhere.
Trigonometry is applied in construction and building, as trigonometry measures right angled triangles.
Plane trigonometry is trigonometry carried out in (on) a plane. This could be contrasted with spherical trigonometry, which is trigonometry carried out on the surface of a sphere. Certainly there are some other more complex forms of trig.