Engineering
Mathematics
Circumradius Inradius and exradius
Question

In a non-right-angled triangle ΔPQR, let p, q, r denote the lengths of the sides opposite to the angles at P, Q, R respectively. The median from R meets the side PQ at S, the perpendicular from P meets the side QR at E, and RS and PE intersect at O. If p =  3, q = 1, and the radius of the circumcircle of the ΔPQR equals 1, then which of the following options is/are correct ?

Area of ΔSOE=312

Length of OE = 16

Radius of incircle of ΔPQR=32(2−3)

Length of RS = 72

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Solution

sinP3=sinQ1=12 R=12

⇒  P=π3  or  2π3   and  Q =π6 or  5π6

Since, p > q ⇒ P > Q

So, if P = π3 and Q=π6 ⇒R=π2 (not possible)

Hence, P = 2π3  and  Q=R=π6

r=Δs=12 (1) ( 3 ) (12)(3+22)=32(2−3)

Now, area of ΔSEF=14 area of ∆PQR

⇒ area of ΔSOE=13  area  of  ΔSEF=112 area of ΔPQR=112 · 34=348

RS=122(3)+2(1)−1=72

OE=PE3=13 · 122(1)2+2(1)2−3=16