# Surface normal: Quiz

Question 1: Surface normals are commonly used in 3D computer graphics for ________ calculations; see Lambert's cosine law.
Incandescent light bulbLight-emitting diodeFluorescent lampLighting

Question 2: In reflection of light, the angle of incidence is the angle between the normal and the ________.

Question 3: If a surface S is given implicitly as the set of points (x,y,z) satisfying F(x,y,z) = 0, then, a normal at a point (x,y,z) on the surface is given by the ________

Question 4: In the two-dimensional case, a normal line perpendicularly intersects the ________ to a curve at a given point.
Trigonometric functionsDerivativeTangentManifold

Question 5: In general, it is possible to define a normal almost everywhere for a surface that is ________.
Metric spaceDerivativeLipschitz continuityArzelà–Ascoli theorem

Question 6: The normal is often used in computer graphics to determine a surface's orientation toward a light source for flat shading, or the orientation of each of the corners (vertices) to mimic a curved surface with ________.

Question 7: If a (possibly non-flat) surface S is parameterized by a system of ________ x(s, t), with s and t real variables, then a normal is given by the cross product of the partial derivatives
Orthogonal coordinatesCurvilinear coordinatesDivergenceEuclidean vector

Question 8: For a ________ in n+1 dimensions, given by the equation r = a0 + α1a1 + α2a2 + ...
Cross-polytopePolytopeSimplexHyperplane

Question 9: Surface normals are essential in defining ________ of vector fields.
Surface integralCurl (mathematics)Vector calculusMultiple integral

Question 10: If F is ________, then the hypersurface obtained is a differentiable manifold, and its hypersurface normal can be obtained from the gradient of F, in the case it is not null, by the following formula
Function (mathematics)Smooth functionDerivativeAnalytic function