Find the equation of the tangents to the curve 3x2 – y2 = 8, which passes through the point (4/3, 0).
assume point (a, b) which lies on the given curve
finding the slope of the tangent by differentiating the curve
m(tangent) at (a,b) is
Since this tangent passes through , its slope can also be written as
Equating both the slopes as they are of the same tangent
b2 = 3a2 – 4a …(i)
Since points (a,b) lies on this curve
3a2 – b2 = 8 …(ii)
Solving (i) and (ii) we get
3a2 – 8 = 3a2 – 4a
a = 2
b = 2 or – 2
therefore points are (2,2) or (2, – 2)
equation of tangent is given by y – y1 = m(tangent)(x – x1)
y – 2 = 3(x – 2)
or
y + 2 = – 3(x – 3)