Page 72 - Math Grade 11 (Advance)

PROEUS DARA

t?!Ql£ 0 <X s ~ , 0 < sinx s ~ Ln~Stl 2bt < x s ~ + 2krc
u

2 2
t?i'i:fl£ 2cos2x + sin xcosx + sinxcos x > 2(sinx + cosx)
2
2(cos\- sin x) + sinxcosx(sinx + cosx)- 2(sinx + cosx) > 0

( cosx + sinx)[2( cosx- sinx) + sinxcosx- 2] > 0
ffitl f(x) = ( COSX + Sinx )[2( COSX- sinx) + SiUXCOSX- 2]

ttnru f(x) thH£?JY2f[:jru'i:fl£2ti 2n: t2lgt?JUlut'dnn'ltu-Hm~nbmsu (O, 2n:) '1
1 I,J ;j' 01 ....
1
t?!Ql£ f(x) = 0 , cosx + sinx = 0 ( 1) ~ 2( cosx- sinx) + sinxcosx- 2 = 0 (2)

( 1 ) : tanx = -1 , ( x = 3n: , x = 7n:) '1
4
4
(2) mb t = cosx-sinx = J2cos(x+~) t[:jru -J2srsJ2

2 . 1-i
t = I- 2sinxcosx , smxcosx = - -
2
2
1 - t 2
(2) ffiutuHtu~ 2t+---2 = o ~ -4t+3 = o
t
2

3n:
t= I ,J2,cos(x+~) = l , cos(x+~) = f =cos~ '1 t?!Ql£ x = 0 ' X - -

3n: 3n: 7n:
X 0 2n:
4 4
+ +
f(x)

7n:
4 + 2b < x < 2n: + 2b ( k E 'Z) '1

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