3sin(2x)-1cos(x)=0

Solution

3 sin (2 x) - 1 cos (x) = 0

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn, x = 0.16744 \dots + 2 πn, x = π - 0.16744 \dots + 2 πn

Solution steps

3 sin (2 x) - 1 \cdot cos (x) = 0

Rewrite using trig identities

- cos (x) + 6 cos (x) sin (x) = 0

Factor

- cos (x) + 6 cos (x) sin (x) : cos (x) (6 sin (x) - 1)

cos (x) (6 sin (x) - 1) = 0

Solving each part separately

cos (x) = 0 or 6 sin (x) - 1 = 0

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

6 sin (x) - 1 = 0 : x = arcsin (\frac{1}{6}) + 2 πn, x = π - arcsin (\frac{1}{6}) + 2 πn

Combine all the solutions

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn, x = arcsin (\frac{1}{6}) + 2 πn, x = π - arcsin (\frac{1}{6}) + 2 πn

Show solutions in decimal form

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn, x = 0.16744 \dots + 2 πn, x = π - 0.16744 \dots + 2 πn

sin (4 x - 3) = cos (5 x - 6)

6 sin (2 x - 3 0^{\circ}) + 2 = 0

sin (x) = sin (\frac{π}{10})

\frac{1}{2} = sin (x)

sin (3 x) - sin (x) = - 2 sin (2 x) sin (x)