Given the equation sin(6π(x+4))=−21 - this is the simplest trigonometric equation This equation is transformed to 6πx+6π=πn+acos(−21) 6πx+6π=πn−π+acos(−21) Or 6πx+6π=πn+32π 6πx+6π=πn−3π , where n - is a integer Move 6π to right part of the equation with the opposite sign, in total: 6πx=πn+2π 6πx=πn−2π Divide both parts of the equation by 6π we get the answer: x1=π6(πn+2π) x2=π6(πn−2π)