Sin7a+sin5a/cos7a-cos5a=2sin(7a+5a/2)cos(7a-5a/2)/-2sin(7a+5a/2)sin(7a-5a/2)=2sin6acosa/2sin6asina . Сокращаем и получаем
cosa/sina=ctga
Sinkv a + coskv a =1
coskv a = 1-sinkv a
9 +5.sinkva -5(1-sinkv a)
9+5.sin kv a -5 + 5.sinkv a = 10 sinkv a +4
<span>a.5a+4a=</span>9a
<span>b.2x+3x+10=5x+10</span>
<span>в.1.5+а+2.5а=1.5+3.5a</span>
<span>г.6у+8+6у=</span>12y+8
<span>д.7m+ m=8m</span>
<span>e.3/8n+ 5/8n+1\3n=1(целая)1\3n</span>
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<span><span>18x-3x+5x=20x</span>
<span>2y-9y=-7y</span>
<span>1.2c-0.3c+5=</span>0.9c+5
<span>2a-15-a+6=a-9</span>
<span>t+6.3t-2.1t=5.2t</span>
<span>5x-5+3x-4x=4x-5</span>
<span>-a-a-a-a=-4a</span>
<span>-2n-2n-2n=-6n</span>
<span>1/3x+1/3x+1/3x=x</span></span>
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