Consider the curve described by the vector parametric equation r(t) = < 0,2cost, sint>
1. sketch the curve c described by r(t) for 0 ≤ t ≤ 2π.
2. find r(π/2) and r'(π/2). indicate both on your sketch.
3. give a vector parametric equation for the tangent line to the curve c at t = π/2.
i have several questions like these but i couldn't get started. trying to work ahead.

Find the value of the cosine for angle a

Which of the following would be a correct step in proving that triangle abc is congruent to triangle cda? a. use a protractor to measure the angles and show that all the corresponding angles are equal in measure. this will allow you to prove congruence by aaa. b. show that segment ab is parallel to segment cd and segment ad is parallel to segment cb. this will allow you to prove congruency by asa. c. show that is segment ab is perpendicular to segment ad. this will allow you to prove congruence by sas. d. none of the above.

The table below shows the angle measurements for triangle abc and triangle xyz. if triangle abc is similar to triangle xyz, what does angle z equal, in degrees?