<PRE><B>Question 358056</B>
The word is theta not theda.


You did not say whay exactly needs to be done here but my guess is proving trig identities.


When proving trig identities, convert everything to sine and cosine.


sec&amp;#952; - cos&amp;#952; = sin&amp;#952;cos&amp;#952;


We know that sec&amp;#952; = 1/cos&amp;#952;.


So, replace sine theta with 1/cos theta.

 

1/cos&amp;#952; - cos&amp;#952; = sin&amp;#952;cos&amp;#952;


On the left side, we simply apply the rules for subtraction of fractions.


The left side becomes (1 - cos^2&amp;#952;)/cos&amp;#952;.


The equation now looks like this:


(1 - cos^2&amp;#952;)/cos&amp;#952; = sin&amp;#952;cos&amp;#952;


Can you take it from here?


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