Question 964110
<pre>
Those are all special angles.  Go here and find them all:

http://mathmistakes.info/facts/TrigFacts/learn/vals/sum.html

The instructions on that page are:

Test yourself on the exact values of the six trigonometric functions at the
"nice" angles. Click on "Show" and "Hide" in each table cell to control which
values are displayed. Work on these values until you know them all!

{{{csc(3pi/4)=sqrt(2)}}}
{{{tan(5pi/4)=1}}}
{{{sin(pi/2)=1}}}

Therefore,

{{{csc(3pi/4)-tan(5pi/4)+sin(pi/2)=sqrt(2)+1+1=2+sqrt(2)}}}

Edwin</pre>