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# AEA Question watch

Question 7: The triangle ABC is inscribed in a circle, AB is the diameter of the circle.

Is it true that the angle ACB is a right angle?
2. yes
3. Thanks. I have:
cotA=b/a
cotB=a/b
cotC =0
and b2=1/2(c2 + a2)
How do I show that cotA, cotB, cotC are consecutive terms of an AP?
4. Show that:
(b/a)-(a/b)=(a/b)-(0)
5. a/b - 0 = a/b = a/(sqrt(2) a) = 1/sqrt(2)
b/a - a/b = (b^2 - a^2)/ab = (2a^2 - a^2)/(sqrt(2) a^2) = 1/sqrt(2)

So cotC, cotB and cotA are consecutive terms of an AP with a common difference of 1/sqrt(2).

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