2014 · Q85
The sides of a triangle are in geometric progression with common ratio r < 1. If the triangle is a right-angled triangle, then r^2 is given by
Elementary MathematicsGeometry
- A(√5+1)/2
- B(√5-1)/2
- C(√3+1)/2
- D(√3-1)/2
Explanation
With sides a, ar, ar^2 (r<1), a^2 = a^2r^2 + a^2r^4 gives r^4 + r^2 - 1 = 0, so r^2 = (√5-1)/2.