Adiza Rabeel

## Math question !?

Question is: Let (c,d) be a point on the circle with the equation x^2+y^2=a^2 (c can not equal a or 0) a) Find d in terms of a and c. b) Find the equation of the tangent to the circle at (c,d) in terms of c and d.

2019-03-20 23:27:58

Question is: Let (c,d) be a point on the circle with the equation x^2+y^2=a^2 (c can not equal a or 0) a) Find d in terms of a and c. b) Find the equation of the tangent to the circle at (c,d) in terms of c and d.

2019-03-20 23:27:58

Aisha Khan

#### This is just a matter of rearranging the equation. You are supposed to be perfectly prepared in that before you get to this stage of the subject.
Given:
x^2 + y^2 = a^2 Substitute c and d.
c^2 + d^2 = a^2 The rule is you can do any valid operation on both sides of an equation and it will still be equal. Subtract c^2.
d^2 = a^2 - c^2 Square root.
d = √(a^2 - c^2) This identifies four points, (±c, ±d).
The tangent is defined as d/c when the circle is centered on the origin.

2019-03-20

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