Question 852881
a)


By definition, sec(x) = 1/cos(x)


So,


cos(53)*sec(53) = cos(53)*1/(cos(53)) = cos(53)/cos(53) = <font size=4 color="red">1</font>


In short, cos(53)*sec(53) = <font size=4 color="red">1</font>


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b)


The <a href="">Pythagorean Trig Identity</a> is: sin^2(x)+cos^2(x) = 1


This is true for any real value x. That means 


sin^2(pi/10)+cos^2(pi/10) = <font size=4 color="red">1</font>


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c)


csc(63) - cot(63)



1/sin(63) - cos(63)/sin(63)



(1 - cos(63))/sin(63)



This is as far as I'm getting. I'm not able to find a result in radical form. So there might be a typo somewhere.