3.70 and 3.700 are some examples to get you started.
Let
. The tangent plane to the surface at (0, 0, 8) is

The gradient is

so the tangent plane's equation is

The normal vector to the plane at (0, 0, 8) is the same as the gradient of the surface at this point, (1, 1, 1). We can get all points along the line containing this vector by scaling the vector by
, then ensure it passes through (0, 0, 8) by translating the line so that it does. Then the line has parametric equation

or
,
, and
.
(See the attached plot; the given surface is orange, (0, 0, 8) is the black point, the tangent plane is blue, and the red line is the normal at this point)
Answer:
The parenthesis means to multiply the numbers. I don't understand any of these either but I hope this helps.
Step-by-step explanation:
Answer:
The first occurence of t for which x = 0 is t = 0.5.
Step-by-step explanation:
The harmonic motion is described by the following equation.

What is the first occurrence of a value of t for which x = 0?
This is t when
. So




The inverse of the cosine is the arcosine. So we apply the arcosine function to both sides of the equality.





The first occurence of t for which x = 0 is t = 0.5.