<p>1)cos3x-cosx=0</p>
<p>2)cos7x+cos3x=2cos2x</p>
<p>3)2cosx*sin3x=sin4x+1</p>
<p>4)cos7x*cos3x=cos4x</p>
<p>5)sqr.3*sinx+cosx=sqr.2</p>
<p>6)sinx+cosx=sqr.2</p>
<p>7)sin5x-sinx=cos3x</p>
<p>Just apply the formula :D. What is your problem?</p>
<p>ee hee hee u have to use this. apply these formulae</p>
<p>sin (x + y) = sinx cosy + cosx siny</p>
<p>and</p>
<p>cos (x + y) = cosx cosy - sinx siny</p>
<p>and know the double, triple, half angle formulae too</p>
<p>but i have to admit
they are way more quickly done w/ a calculator… :)</p>
<p>be sure to set it to radians, not degrees
i find radians easier</p>
<p>can you solve a couple of them please? I’m bad at trigonometry.</p>
<p>I really need to solve these questions.</p>