1)

Let PQR  be a triangle of area with a=2,b=72 and c=52 where a,b and c  the length of the sides of the triangle opposite to the angle s  at P, Q and R respectively.Then 2sinPsin2P2sinP+sin2P equal to 


A) 34

B) 454

C) (34)2

D) (454)2

Answer:

Option C

Explanation:

 Concept involved if ABC has sides a, b, c then, 

18112021729_l1.PNG

 tan(A/2)=(sb)(sc)a(sa)

 where, s=a+b+c2

 Sol ,s=2+72+522=4

        2sinPsin2P2sinP+sin2p=2sinP(1cosP)2sinP(1+cosP)

 =2sin2(P/2)2cos2(P/2)=tan2(P/2)

18112021339_l2.PNG

       (sb)(sc)s(sa)×(sb)(sc)(sb)(sc)

      ((sb)(sc)2)2=(4+72)2(452)22

 =(34)2