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شائع علم المثلثات >

(sin(x)(2cos(x)+1))/(sin(x)+cos(x))<0

الحلّ

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} < 0

الحلّ

\frac{2 π}{3} + 2 πn < x < \frac{3 π}{4} + 2 πn or π + 2 πn < x < \frac{4 π}{3} + 2 πn or \frac{7 π}{4} + 2 πn < x < 2 π + 2 πn

تدوين الفاصل الزمني

(\frac{2 π}{3} + 2 πn, \frac{3 π}{4} + 2 πn) \cup (π + 2 πn, \frac{4 π}{3} + 2 πn) \cup (\frac{7 π}{4} + 2 πn, 2 π + 2 πn)

عشري

2.09439 \dots + 2 πn < x < 2.35619 \dots + 2 πn or 3.14159 \dots + 2 πn < x < 4.18879 \dots + 2 πn or 5.49778 \dots + 2 πn < x < 6.28318 \dots + 2 πn

خطوات الحلّ

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} < 0

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )}

دوريّة:

2 π

:

مركّبة من الدوالّ والدوريّات التالية

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )}

2 π

مع دوريّات

sin (x)

:

الدوريّة المركّبة للدالّة هي

= 2 π

Find the zeroes and undifined points of

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )}

for

0 \leq x < 2 π

To find the zeroes, set the inequality to zero

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} = 0

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} = 0, 0 \leq x < 2 π : x = 0, x = π, x = \frac{2 π}{3}, x = \frac{4 π}{3}

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} = 0, 0 \leq x < 2 π

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

sin (x) (2 cos (x) + 1) = 0

حلّ كل جزء على حدة

sin (x) = 0 or 2 cos (x) + 1 = 0

sin (x) = 0, 0 \leq x < 2 π : x = 0, x = π

sin (x) = 0, 0 \leq x < 2 π

sin (x) = 0 :

حلول عامّة لـ

sin (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn

حلّ:

x = 2 πn

x = 0 + 2 πn

0 + 2 πn = 2 πn

x = 2 πn

x = 2 πn, x = π + 2 πn

0 \leq x < 2 π :

حلول للمدى

x = 0, x = π

2 cos (x) + 1 = 0, 0 \leq x < 2 π : x = \frac{2 π}{3}, x = \frac{4 π}{3}

2 cos (x) + 1 = 0, 0 \leq x < 2 π

انقل

1

إلى الجانب الأيمن

2 cos (x) + 1 = 0

من الطرفين

1

اطرح

2 cos (x) + 1 - 1 = 0 - 1

بسّط

2 cos (x) = - 1

2 cos (x) = - 1

2

اقسم الطرفين على

2 cos (x) = - 1

2

اقسم الطرفين على

\frac{2 cos ( x )}{2} = \frac{- 1}{2}

بسّط

cos (x) = - \frac{1}{2}

cos (x) = - \frac{1}{2}

cos (x) = - \frac{1}{2} :

حلول عامّة لـ

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

0 \leq x < 2 π :

حلول للمدى

x = \frac{2 π}{3}, x = \frac{4 π}{3}

وحّد الحلول

x = 0, x = π, x = \frac{2 π}{3}, x = \frac{4 π}{3}

Find the undefined points:

x = \frac{3 π}{4}, x = \frac{7 π}{4}

Find the zeros of the denominator

sin (x) + cos (x) = 0

Rewrite using trig identities

sin (x) + cos (x) = 0

cos (x) \neq = 0, cos (x)

اقسم الطرفين على

\frac{sin ( x ) + cos ( x )}{cos ( x )} = \frac{0}{cos ( x )}

بسّط

\frac{sin ( x )}{cos ( x )} + 1 = 0

\frac{sin ( x )}{cos ( x )} = tan (x)

:Use the basic trigonometric identity

tan (x) + 1 = 0

tan (x) + 1 = 0

انقل

1

إلى الجانب الأيمن

tan (x) + 1 = 0

من الطرفين

1

اطرح

tan (x) + 1 - 1 = 0 - 1

بسّط

tan (x) = - 1

tan (x) = - 1

tan (x) = - 1 :

حلول عامّة لـ

tan (x)

periodicity table with

πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = \frac{3 π}{4} + πn

x = \frac{3 π}{4} + πn

0 \leq x < 2 π :

حلول للمدى

x = \frac{3 π}{4}, x = \frac{7 π}{4}

0, \frac{2 π}{3}, \frac{3 π}{4}, π, \frac{4 π}{3}, \frac{7 π}{4}

ميّز المقاطع المختلفة

0 < x < \frac{2 π}{3}, \frac{2 π}{3} < x < \frac{3 π}{4}, \frac{3 π}{4} < x < π, π < x < \frac{4 π}{3}, \frac{4 π}{3} < x < \frac{7 π}{4}, \frac{7 π}{4} < x < 2 π

لخّص في جدول

sin (x) 2 cos (x) + 1 sin (x) + cos (x) \frac{s i n ( x ) ( 2 c o s ( x ) + 1 )}{s i n ( x ) + c o s ( x )} x = 0 0 + + 0 0 < x < \frac{2 π}{3} + + + + x = \frac{2 π}{3} + 0 + 0 \frac{2 π}{3} < x < \frac{3 π}{4} + - + - x = \frac{3 π}{4} + - 0 غير معرّف \frac{3 π}{4} < x < π + - - + x = π 0 - - 0 π < x < \frac{4 π}{3} - - - - x = \frac{4 π}{3} - 0 - 0 \frac{4 π}{3} < x < \frac{7 π}{4} - + - + x = \frac{7 π}{4} - + 0 غير معرّف \frac{7 π}{4} < x < 2 π - + + - x = 2 π 0 + + 0

< 0 :

ميّز المقاطع التي تحقّق الشرط

\frac{2 π}{3} < x < \frac{3 π}{4} or π < x < \frac{4 π}{3} or \frac{7 π}{4} < x < 2 π

\frac{sin ( x ) ( 2 cos ( x ) + 1 )}{sin ( x ) + cos ( x )} :

استخدم دوريّة الـ

\frac{2 π}{3} + 2 πn < x < \frac{3 π}{4} + 2 πn or π + 2 πn < x < \frac{4 π}{3} + 2 πn or \frac{7 π}{4} + 2 πn < x < 2 π + 2 πn

أمثلة شائعة

2sin^2(x)+3sin(x)+1<0

2 sin^{2} (x) + 3 sin (x) + 1 < 0

sin(x)<= 0.5

sin (x) \leq 0.5

sin(x/2)+cos(x/2)<1

sin (\frac{x}{2}) + cos (\frac{x}{2}) < 1

sin(t)>0

sin (t) > 0

sin(x)-cos(x)>= 0

sin (x) - cos (x) \geq 0