Answer:
45°
Explanation:
θ = arctan(1) = 45°
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Make sure your calculator is in degrees mode.
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Additional comment
The tan⁻¹( ) function is the inverse tangent function. It can be read as "arctangent of ..." or "the angle whose tangent is ...". In spreadsheets and some calculators, it comes in two flavors: ATAN(x) and ATAN2(x, y). The latter is useful for finding the angle associated with a vector whose components are known, and that can be in any of the four quadrants.
Calculators will give an angle in degrees or radians according to the mode that is set. Spreadsheets always give the angle in radians. The range of a calculator tan⁻¹( ) or ATAN( ) function is -π/2 to π/2 radians, or -90° to 90°.