What is the general solution for sin(2x)sec(x)+2cos(x)=0 ?

The general solution for sin(2x)sec(x)+2cos(x)=0 is x=(3pi)/4+pin

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Popular >

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

Solution

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

Solution

x = \frac{3 π}{4} + πn

Degrees

x = 13 5^{\circ} + 18 0^{\circ} n

Solution steps

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

Rewrite using trig identities

2 cos (x) + sec (x) sin (2 x)

Use the Double Angle identity:

sin (2 x) = 2 sin (x) cos (x)

= 2 cos (x) + sec (x) \cdot 2 sin (x) cos (x)

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

Factor

2 cos (x) + 2 cos (x) sec (x) sin (x) : 2 cos (x) (1 + sec (x) sin (x))

2 cos (x) + 2 cos (x) sec (x) sin (x)

Rewrite as

= 1 \cdot 2 cos (x) + 2 cos (x) sec (x) sin (x)

Factor out common term

2 cos (x)

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

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

Solving each part separately

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

cos (x) = 0 : x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

cos (x) = 0

General solutions for

cos (x) = 0

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

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

1 + sec (x) sin (x) = 0 : x = \frac{3 π}{4} + πn

1 + sec (x) sin (x) = 0

Rewrite using trig identities

1 + sec (x) sin (x)

sec (x) sin (x) = tan (x)

sec (x) sin (x)

Express with sin, cos

sec (x) sin (x)

Use the basic trigonometric identity:

sec (x) = \frac{1}{cos ( x )}

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

Simplify

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

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

Multiply fractions:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

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

Multiply:

1 \cdot sin (x) = sin (x)

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

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

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

Use the basic trigonometric identity:

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

= tan (x)

= 1 + tan (x)

1 + tan (x) = 0

Move

1

to the right side

1 + tan (x) = 0

Subtract

1

from both sides

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

Simplify

tan (x) = - 1

tan (x) = - 1

General solutions for

tan (x) = - 1

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

Combine all the solutions

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

Since the equation is undefined for:

\frac{π}{2} + 2 πn, \frac{3 π}{2} + 2 πn

x = \frac{3 π}{4} + πn

Popular Examples

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tan (x) = \frac{6}{4}

cot(x)sin^2(x)=4cot(x)

cot (x) sin^{2} (x) = 4 cot (x)

solvefor x,sin(x)+cos(y)=sin(x)cos(y)solve for

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x, z = arctan (\frac{x}{y})

Frequently Asked Questions (FAQ)

What is the general solution for sin(2x)sec(x)+2cos(x)=0 ?
The general solution for sin(2x)sec(x)+2cos(x)=0 is x=(3pi)/4+pin