Calculus III Exam Review

1. Calculus III Exam Review AshishHeda Peter Zhu

2. List of Topics 11.5 • Equation of Line • Equation of Plane • Types of Lines/Planes • Distance (from point to line/plane or from line to plane) • Line/Angle of Intersection between Planes 11.6 • Visualize/Name the Equation 12.1 • Rules for Differentiating Vector Functions • Velocity. Speed, Acceleration 12.2 • Integration of Vector Functions • Initial Value Problem/Projectile Motion • Rules for Integrating Vector Functions 12.3 • Arc Length • Arc Length Parameterization • Speed On Smooth Curve 12.4 • Unit Tangent Vector • Normal Vector • Curvature • Osculating Circle & Radius of Curvature 12.5 • Tangential and Normal Acceleration • Binormal Vector • Torsion 12.6 • Velocity and Acceleration in Polar Coordinates Possible Tricky Problems

3. Return to List of Topics Equation of Line Recall that in 2D the equation of a line is given by: where m represents the slope In three dimensions we have a similar equation: *Note the bolded terms show these are vectors rather than scalar values

4. Return to List of Topics Equation of Plane You need a way of describing every point on a plane. What is something every line on the plane will have in common? Answer: all lines make a 90° angle with the normal vector of the plane and thus, the dot product of the normal line and any line on the plane is 0.

5. Continued

6. Return to List of Topics Types of Lines

7. Types of Planes

8. Return to List of Topics Distance From Point to Line

12. Return to List of Topics Distance From Point to Plane Similar to finding distance from point to a line, except that you are given the slope of the perpendicular line!

13. How can you find a Point P on the plane? Use the equation of the plane and set any two variables to 0 and solve for the other:

15. Return to List of Topics Line/Angle of Intersection of Two Planes In order to determine the angle/line of intersection take a look at the following picture: The normal vectors of two planes can be easily obtained. What can you say about the angles depicted in the picture to the left?

16. How can you determine the angle between the two normal lines?

17. How can you determine the slope of the line of intersection? Now all you need is a point on the line and you can find the line of intersection.

18. From here you can find theta and determine the angle between the planes. Remember that there are always 2 possible angles between planes! Usually you are asked to provide the acute angle.

19. Line of Intersection Now we need a point. This is any point that satisfies both of the above equations. There are lots of methods for doing this but here is one:

20. Return to List of Topics Visualize/Name the Equation What type of equation is it? What does it look like? Parabola that goes forever along the x-axis

21. Cylinder (with elliptical base) Ellipsoid Paraboloid

22. Hyperboloid (two unconnected regions) Hyperboloid (two connected regions)

23. Return to List of Topics Rules for Differentiation of Vector Functions

24. Velocity, Speed, Acceleration

25. Problem 23 from section 12.1 • Does the particle have constant speed? If so, what is it? • Is the particle’s acceleration vector always orthogonal to its velocity vector? • Does the particle move clockwise or counterclockwise around the circle? • Does the particle begin at the point (1,0)?

26. Return to List of Topics Integration

27. Return to List of Topics Initial Value Problems of Vector Functions

28. Projectile Motion A projectile is fired with an initial speed of 500 m/s at an angle of elevation of 45° • When and how far away will the projectile strike? • How high overhead will the projectile be when it is 5 km downrange? • What is the greatest height reached by the projectile? First, thing is convert this into a problem like the one before:

29. Possible information you may need to know • Acceleration due to gravity in m/s2 and ft/s2 • How many meters in a kilometer (km) …

30. Return to List of Topics Rules for Integration of Vector Functions (see problem 33 of 12.2 for more material) Note that there is no property listed for a non-constant vector crossed with r(t).

31. Return to List of Topics Arc Length Along a Curve Recall that for 2D, the arc length is given by: Thus, it makes sense that in 3D, the arc length is given by:

33. Return to List of Topics Arc Length Parameterization with base point Sometimes we want to know what is the arc length from an initial position to any given position at time, t. Ex. Tracking a satellite: you know its initial position where it was put into outer space and you know the path it will follow. You want to design a formula so that at any given time you know how much distance it has traveled

35. Return to List of Topics Find the arc length parameter along the curve form the point where t = 0 for the curve: Then, re-write the curve as function of the arc length parameter.

36. Return to List of Topics Speed on Smooth Curve

37. Return to List of Topics Unit Tangent Vector Represents the change in direction of the curve with respect to time or the direction of the velocity at anytime, t.

38. Return to List of Topics Normal Vector This is change of the change in direction of the curve with respect to time or the change in of the direction of velocity with respect to time.

39. Return to List of Topics Binormal Vector Has physics and other applications but it is important for completing the Frenet frame. This is similar to the xyz frame except unlike the xyz frame this frame travels with the curve.

40. Return to List of Topics Cuvature The rate at which the direction of the curve changes with respect to the distance traveled. Best way to think about curvature is driving a car. If the direction of travel changes from driving north to driving east in 1 mile then it not that difficult of a turn to make. On the other hand going from north to east in a matter of 100ft is much harder and thus a much greater curvature.

41. You can also think of it in terms of driving along a circle: Imagine you are going at 100 mph around the following two circles: Harder to drive around Easier to drive around R=100 ft R=5,280ft

42. Thus, curvature can be approximated by: The actual formula is:

43. Computational Formula of Curvature

44. Return to List of Topics Osculating Circle or Circle of Curvature and the Radius of Curvature • Tangent to the curve at P (has the same tangent line the curve has) • Has the same curvature the curve has at P • Has center located along the direction of the Normal vector. • Radius of curvature =

45. Tangential and Normal Components of Acceleration An easy way to understand this is that the tangential component of a(t) points in the direction of the unit tangent vector (or the velocity vector) and similarly the normal component of a(t) points in the direction of the normal vector.

47. Return to List of Topics Torsion Rate at which the osculating plane turns about T as P moves along the curve. Measures how the curve twists.

48. Computational formula

49. Possible Tricky Questions (True/False)Three statements: I. Two perpendicular lines to a plane are parallel II. III. The derivative of the arc length is the velocity. (answer: T, T, F (derivative of arc length is speed) (Types of Planes, Rules of differentiation or integration, acceleration components, arc length, and curvature concepts…)

50. Return to List of Topics • May give you 4 points and ask you if all lie on the same plane • Distance from a line to a plane (be careful to check that the line does not intersect the plane) • Ask you to re-write a curve with the arc length parameter (this means you should provide r(s))