From SOH CAH TOA, you know that
cos(72°) = 6/x
x = 6/cos(72°) ≈ 6/0.309017
x ≈ 19.42
Hello, the answer is x=-1/2
Here are the steps....
<span><span><span><span><span>−<span>7x</span></span>+12</span>+</span>−<span>2x</span></span>=<span>23+<span>13x</span></span></span><span><span><span>(<span><span>−<span>7x</span></span>+<span>−<span>2x</span></span></span>)</span>+<span>(12)</span></span>=<span><span>13x</span>+23</span></span>(Combine Like Terms)<span><span><span>−<span>9x</span></span>+12</span>=<span><span>13x</span>+23</span></span><span><span><span>−<span>9x</span></span>+12</span>=<span><span>13x</span>+<span>23
</span></span></span><span><span><span><span>−<span>9x</span></span>+12</span>−<span>13x</span></span>=<span><span><span>13x</span>+23</span>−<span>13x</span></span></span><span><span><span>−<span>22x</span></span>+12</span>=<span>23
</span></span><span><span><span><span>−<span>22x</span></span>+12</span>−12</span>=<span>23−12</span></span><span><span>−<span>22x</span></span>=<span>11
</span></span><span><span>−<span>22x</span></span><span>−22</span></span>=<span><span><span>11<span>−22</span></span></span></span><span>x=<span><span><span>−1</span>2</span></span></span><span>
</span>Hope this helps you!!