triangle QPR is a right angled triangle, right angled at Q and the points S and T trisect the side QR.prove that 8PT2 =3PR2 +5PS2.

Hi!
Here is the answer to your question.
 
Since, S and T trisect the side QR.
∴ QS = ST = TR
Let QS = ST = TR = k (say)
∴ QT = 2k and QR = 3k
 
In right ∆PQS,
PS2 = PQ2 + QS2  (Pythagoras Theorem)
⇒ PS2 = PQ2 + k2 
 
In right ∆PQT,
PT2 = PQ2 + QT2              
⇒ PT2 = PQ2 + (2k)2 
⇒ PT2 = PQ2 + 4k2 
 
In right ∆PQR,
PR2 = PQ2 + QR2 
⇒ PR2 = PQ2 + (3k)2 
⇒ PR2 = PQ2 + 9k2 
 

Cheers!

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