Question

(20 PONTOS) Simplifique:

$E=\dfrac{\cos y-\cos x}{\sec x-\sec y}$

Answer 1

 A resposta segue anexa. 

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18/02/2016 
Sepauto - SSRC
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Answer 2

$\boxed{\begin{array}{l}\sf E=\dfrac{cos(y)-cos(x)}{sec(x)-sec(y)}=\dfrac{cos(y)-cos(x)}{\frac{1}{cos(x)}-\frac{1}{cos(y)}}\\\\\sf E=\dfrac{cos(y)-cos(x)}{\frac{cos(y)-cos(x)}{cos(x)\cdot cos(y)}}=\diagup\!\!\!\!\!\![cos(y)-\diagup\!\!\!\!\!\!cos(x)]\cdot\dfrac{cos(x)\cdot cos(y)}{\diagup\!\!\!\!\!\![cos(y)-\diagup\!\!\!\!\!\!cos(x)]}\\\\\huge\boxed{\boxed{\boxed{\boxed{\sf E=cos(x)\cdot cos(y)}}}} \end{array}}$