The center of a circle is (1,6) The circle passes through the point (-1,8). What is its radius?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Can someone me with this graph problem by the way i need to know the answers by today since this assignment is due ! !

Match the following reasons with the statements given to create the proof. 1. do = ob, ao = oc sas 2. doc = aob given 3. triangle cod congruent to triangle aob vertical angles are equal. 4. 1 = 2, ab = dc if two sides = and ||, then a parallelogram. 5. ab||dc if alternate interior angles =, then lines parallel. 6. abcd is a parallelogram cpcte