If 15 cotA = 8, find the values of sinA and secA.
We have, 15 cotA = 8
→ cotA = (8k)/(15k) = 1/tanA = AC/BC (For some value of k)
By Pythagoras theorem, (hypotenuse)2 = (perpendicular)2 + (base)2
∴AB2 = BC2 + AC2
AB2 = (15k)2 + (8k)2
AB2 = 225k2 + 64k2
AB2 = 289k2
= (17k)2
→ AB = 17k
∴ sinA = BC/AB = (15k)/(17k) = 15/17
secA = 1/cosA = AB/AC = (17k)/(8k) = 17/8
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