There are two questions, I can solve the first one but not the second one with the same method.(adsbygoogle = window.adsbygoogle || []).push({});

find the exact value of cot pi/4 in surd form.

cot pi/4

= 1/ tan (pi/4)

= 1 / tan 45 ( in degrees)

= 1 / 1

= 1

which is the right answer according to the book.

However when I tried the next question - sec 5 * pi / 4, there are problems.

sec 5 * pi / 4

= 1 / cos (5 * pi / 4)

= 1 / cos (900/4) ( in degrees)

= 1/ cos(225)

and then I am stuck here. How do I express this in surd form?

The correct answer is minus(2^0.5)

and all I know is cos45 = 1/root2, cos30 = root3/2 and cos 60 = 0.5

Can someone help me get to the correct answer?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Trig Function

**Physics Forums | Science Articles, Homework Help, Discussion**