Question

find delta in each of the following case:

tan delta=-0.75

Answer 1

The domain of tan(x) is from -π/2 to π/2. So the reference angle for tan(δ)=-0.75 is between -&pi/2; to 0.
Having found the reference angle δ (approx. -0.64 radians), the general solution will be
δ+kπ where k=an integer.

Answer 2

so what will be the solution

Answer 3

A pre-calculus answer is -0.64 + kπ radians, where k∈ℤ.

Answer 4

The reason for the kπ is because tangent is a periodic function, with period equal to π radians.

Also, for your solution, you will need to evaluate more accurately (accuracy according to instructions, 3-4 decimals normally) the value of arctan(-0.75).