Solving a line and circle simultaneously
Substitute into an origin-centred circle equation.
- The same pair of values must satisfy both equations.
- For elimination, multiply every term of an equation by the same number. For substitution, replace a variable by an equal expression.
- Substitute the final pair into both original equations to check.
Example 1
Find both intersection points.
Example 2
Find both intersection points.
Your turn
Question 1 Substitute this -value into the circle equation. Square 3. Take both square roots to find both -coordinates. Pair each -value with .
Find both intersection points.
Check answer
Question 2 Substitute this -value into the circle equation. Square 4. Take both square roots to find both -coordinates. Pair each -value with .
Find both intersection points.
Check answer
Question 3 Substitute this -value into the circle equation. Square 5. Take both square roots to find both -coordinates. Pair each -value with .
Find both intersection points.
Check answer
Question 4 Substitute this -value into the circle equation. Square 6. Take both square roots to find both -coordinates. Pair each -value with .
Find both intersection points.
Check answer
Question 5 Substitute this -value into the circle equation. Square 7. Take both square roots to find both -coordinates. Pair each -value with .
Find both intersection points.
Check answer
Find both intersection points.
Find both intersection points.
Find both intersection points.
Find both intersection points.
Find both intersection points.