- Math Educators Forum
- New student club re K-12 math certification
- Interest meeting Tuesday, Sept. 15, 7:30 PM, South 328
- Math 101
- “Welcome to the major” seminar
- Good for 1st semester students early in major to take
- Section 12.1
- 8 octants
- 3 coordinates to specify points, e.g., (0,0,3)
- Direction of coordinates matters
- Equations define shapes that can be parallel / perpendicular to features of coordinate system
- 3D distance formula (Pythagorean theorem)
- Distance from (x1, y1, z1 )
to (x2, y2, z2 ) is
- √( (x2-x1)2 + (y2-y1)2 + (z2-z1)2 )
- Sphere has equation like circle with added variable
- √( (x2-x1)2 + (y2-y1)2 + (z2-z1)2 )
- Distance from (x1, y1, z1 )
to (x2, y2, z2 ) is
- Equations won’t work quite the same as in 2D
- 8 octants
- Some shapes
- Lines?
- y = x and z = 0
- y = x and z = 5
- x = y = z
- Notice how lines are systems of 2 equations
- Planes?
- Generally defined by single linear equation
- x + y + z = 1
- ax + by + cz = d
- Spheres?
- (x-a)2 + (y-b)2 + (z-c)2 = r2
- (r = radius, (a,b,c) is center)
- Lines?
- Problem set
- Quadric surfaces
- Read section 12.6