You are not logged in.
Pages: 1
dear affirmation;
if you look carefully you will see this
if x=18 so cos3x=sin2x
=cos2x.cosx-sin2x.sinx=2sinx.cosx
=cos2x.cosx-2sin^2.cosx=2sinx.cosx
=cos2x-2sin^2=2sinx
=1-2sin^2-2sin^2=2sinx
=4sin^2+2sinx-1=0
so Δ=2√5
then sinx=(√5-1)\4 sinx=(√5+1)\4 second value doesn't provide the equation
so true value is sin18=(√5-1)\4
now dear ganesh please solve this
cos2∏\11+cos4∏\11+cos6∏\11+cos8∏\11+cos10∏\11=?
the value is a rational
tan.tan=(sin.sin)\(cos.cos)
tan.tan.cos=(sin.sin)\(cos.cos)\cos
=(sin.sin)\cos
=(sin\cos).sin
=tan.sin
if tan.cot=1
(1-tan)\(1+tan)=(cot-1)\(cot+1)
cot+1-tan.cot-tan=cot-1+tan.cot-tan
so 1-tan.cot=tan.cot-1
2=2tan.cot
tan.cot=1
(sin+cos)\(sin-cos)=[(sin\cos)+1]\[(sin\cos)-1]
=[(sin+cos)\cos]\[(sin-cos)\cos]
=(sin+cos)\(sin-cos)
so (sin+cos)\(sin-cos)=(sin+cos)\(sin-cos)
the value of sixth question is 1/7
the value of fifth question is 17/19
the value of forth question is 1/7
value of third question is -9/7
the value of second question is 1
if sinA=5/13 so cosA=12/13 then sinA/cosA=tanA (5/13)/(12/13)=5/12=tanA
Pages: 1