Statement I: If in a `DeltaABC,BC=(p)/(|p|)-(q)/(|q|)` and `C=(2p)/(|p|),|p|ne|q|`, then the value of `cos2A+cos2B+cos2C` is -1.
Statement II: If in `DeltaABC,angleC-90^(@)`, then
`cos2A+cos2B+cos2C=-1`

If in a triangleABC, BC=(e)/(|e|)-(f)/(|f|) and AC=(2e)/(|e|): |e|ne|f|, then the value of cos2A+cos2B+cos2C must be

Assertion : If in a /_\ABC, vec(BC)=vecp/|vecp|-vecq/|vecq| and vec(AC)=(2vecp)/|vecp|,|vecp|!=|veq| then the value of cos2A+cos2B+cos2C is -1., Reason: If in /_\ABC, /_C=90^0 then cos2A+cos2B+cos2C=-1 (A) Both A and R are true and R is the correct explanation of A (B) Both A and R are true R is not te correct explanation of A (C) A is true but R is false. (D) A is false but R is true.

In DeltaABC , prove that: cos2A+cos2B-cos2C=1-4sinAsinBcosC

If A+B+C=270^@ , then cos2A+cos2B+cos2C+4sinAsin B sinC=

In any DeltaABC, 2 [bc cos A + ca cos B+ ab cos C]=

If A+B+C =(3pi)/(2) , then cos2A+cos2B+cos2C is equal to-

In a DeltaABC, cos""(A)/(2)cos""(B)/(2)cos""C/(2) is

If A+B+C=pi , prove that : cos2A+cos2B+cos2C=-1-4cosA cosB cosC

In DeltaABC , prove that: a(cosC-cosB)=2(b-c)cos^(2)A/2

In a DeltaABC , a(cos^(2)B+cos^(2)C)+cosA( c cosC+bcosB)=