cos^2x - sin<span>^2x = 1.
cos^2 4x=1
4x=2piN
x=PiN/2</span>
0,63*0,15*0,44/0,03*0,88*0,81=<span>0.9879408
</span>0,63*015*0,44/0,03*0,88*0,81=<span>98.79408</span>
<span>(4 1/9 - а) + 8 5/9=9 2/9</span>
<span>37/9 - a + 77/9 - 83/9 = 0</span>
-a = -31/9 :(-1)
a = 31/9 = 3 4/9
<span>5 3/7 - (b-2 1/7)=2 4/7</span>
<span>38/7 - b + 15/7 - 18/7 = 0</span>
<span>-b = -35/7 :(-1)</span>
<span>b = 35/7 = 5</span>