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AHHH PLEASE HELP MEH
Evaluate (cot90)(cos45) + sec45 exactly. No decimals allowed, rationalize if necessary


Sagot :

Answer:  [tex]\sqrt{2}[/tex]

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Explanation:

Rewrite each trig function terms of sine and/or cosine. Then use the unit circle to find that,

[tex]\cot(90^{\circ})\cos(45^{\circ}) + \sec(45^{\circ})\\\\\frac{\cos(90^{\circ})}{\sin(90^{\circ})}\cos(45^{\circ}) + \frac{1}{\cos(45^{\circ})}\\\\\frac{0}{1}*\frac{\sqrt{2}}{2} + \frac{1}{(\sqrt{2})/2}\\\\\frac{2}{\sqrt{2}}\\\\[/tex]

Now rationalize the denominator

[tex]\frac{2}{\sqrt{2}}\\\\\frac{2\sqrt{2}}{\sqrt{2}*\sqrt{2}}\\\\\frac{2\sqrt{2}}{\sqrt{2*2}}\\\\\frac{2\sqrt{2}}{\sqrt{4}}\\\\\frac{2\sqrt{2}}{2}\\\\\sqrt{2}[/tex]

Which is the exact value of [tex]\sec(45^{\circ})[/tex]

The portion [tex]\cot(90^{\circ})*\cot(45^{\circ})[/tex] evaluates to 0 and goes away.