!"# $%$ #&'()*+,*-*+,. $/0'*12+,2*+,. 3 '4+5678 ' - - !"#$ - %&'()(*+,(- 9:;<6=)7! > 8!"? ( ) +@ π A 5BC!D sin2x – 2sinx – cosx + 1 = 0. /)EF * 7 8 G 7 8 GH* . * = + = − 9 :!I;<6A <J ( ) , * *+,. *+,K + + = 9 9!)LMN5,OE )P/*+EQRS",+ E9:;<6GEST<J,+E<BU5:T*E ) P/*EQ9 >V0EF ( ) ' , * . K *+,. *+,. *+,* *+,. *+,* *+,, *+,. *+,* *+,, *+,+ @ @ @ @ ,W ,W *W ,W *W .W ,W *W .W KW = = + = + + = + + + ( ) *+,. *+,* *+,, 9999 ,W *W .W = + + + n soá haïng :!I;<6A , * . ,O 999 = + + + + 9 9:;<6=)A =5BC!D * * * * 7 ,8 * 7 ,8 , 7 8 , , 9 + = + + + = ÷ 9:;<6=)A 5BC!D * * X K + + + = 9 9 M/EFY?&Z G!? !JA [JSZ ,* 4 * * O , . = − + + ÷ ÷ ÷ 9:;<6!IA 9 !)\5] <LG0Z%^L_5!)L<B3!` [_%7-,@,8^7.@+87K@.8P/7,@)89:!I;<6A )a )%^Y%^bc^b,+%bX#M/!S<J)Y%^dM/ <J)e)!"Y^9:;<6!I[fTA %dHd#9 !)\5] <LG0%7,@.8^7g*@,87g,@g.89h5U5 <J)#i )V<jS?= * * * ,++ + + = M/)L<B3!`9:!I; <6A <Lk)P/[?:A <B3!`<9 !" !"#$%& ! '(%)*+! ,-./0! !"# $%$ #&'()*+,*-*+,. #$%&'() *+","--./01-2."3-"4 56 7+ E , 7*E ,87E ,8 + *E , + X 7+@ 8 O X %$ π π π = ⇔ − − = ⇔ − = = ⇔ ∈ = +O*.O4 *X,144 ≈ ≈ ,+ , * + − > 9$h5P/)0: * 7 *+,.8 * *+,K . * + + + = − 9lM=EMPmD)<BU =) +44c,, c.K4Xc+. & & ≈ ≈ − ,+ ,+ ,+ , 4 4 , ,O *+ ,O *+ ,O *+ ,+ .O 9 9 , + + + = − d≈+4cK1+ ,+ *+,K ,' ' ' W 1 1 1 1 − = + = + = + = %nb+%b+^b+b+9 S<TM"oGb,Obpq K4cO1*.c+4 ,+ * * * , , * 7,8 , , , 7*8 , , , 7*8 * . + . , X + = + ÷ ⇔ + + + = ⇔ + + + − = ⇔ + = − ÷ ÷ ⇒ + = − <BU' * * X , + . , + + + = + + = +,1,O1 Oc*cK* +.c,4X *X,c+. ≈ − ≈ − ≈ − ≈ − ,+ * * * X 7,8 . , X * * , X 7*8 7,8 +OX,OO@ 7*8 *14,*c + = + + = + − = ÷ ÷ − − = + ⇔ ≈ ⇔ ≈ − +OX,OO *14,*c ≈ ≈ − ,+ • FYrsSA 4 * O − ÷ M/ ( ) . 4 . . 4 , 4 7 O8 9 O & − − ⇒ = − • FYrsSA ,* * , . + ÷ M/ ccK,KcOO& ≈ − ,+ ( ) K ,* *K . c ,* * ,* 7 .8 9 . & − − − ⇒ = th0 , * ccK,KcOO& & &= + ≈ − B3!`sS .<J)%^5BC!D' * * .1 O1 X + ,. ,. ,. + − − − = ?_U55BC!DGb, D)<BU*!I)' KcO4K4 +K1Kcc - - ≈ ≈ − KcO4K4 +K1Kcc - - ≈ ≈ − ,+ #u<FGZ#sS ^9 d#Hd%bd#uHd% ≥ #u% d#Hd%iT?#ud% ]/ v V D)<BU K E^b O 5>o<IM:E! w V D)<BU w 1c14+c ≈ w 1c14+c ≈ ,+ ( ) ( ) ( ) ( ) ( ) ( ) * * * * * * * * * * * * * *+ , . * , , . ,++ . . K * 1O + K * *O + . . + + = ⇔ − + − + + + − + + + + = ⇔ + + − − = ⇔ + + − − = k) * , *.+ @ . . . 2 3 − = ÷ +XXXXX@ + O+OO*O 2 3 − ÷ ≈ ,+ %-8 - ./0123(- - .$*456*7822(-9:/ *7 ()23(- - ;</"#123(- . O+OO*O 2 3 − ÷ ≈ ,+ % - 8 - ./0123( - - .$*456*7822( - 9:/ *7 ()23( - - ;</"#123( - . = ?_U55BC!DGb, D)<BU*!I)' KcO4K4 +K1Kcc - - ≈ ≈ − KcO4K4 +K1Kcc - - ≈ ≈ − ,+ #u<FGZ#sS ^9 d#Hd%bd#uHd% ≥ #u% d#Hd%iT?#ud% ]/ v V D)<BU K E^b O 5>o<IM:E! w. #&'()*+, *-* +,. #$%&'() *+"," - - ./01 -2 ." 3- "4 56 7+ E , 7*E ,87E ,8 + *E , + X 7+@ 8 O X %$