Question

Is sin x+ cos x=1 is a trigonometric equation?If yes why ?

Answer 1

By definition, a trig equation is an equation that contains one or many trig functions.
sin x + cos x = 1
This trig equation has 2 trig functions, the function f(x) = sin x, and the function g(x) = cos x.
The variable x is an arc that rotates counter-clockwise on the trig unit circle. The arc x is measured in degrees or radian `(pi/5, pi/6...)`.
When the arc x rotates, its projections on 4 axis varies and create the 4 basic trig functions: f(x) = sin x, g(x) = cos x; h(x) = tan x, and i(x) = cot x.