Question

find the value of
$\sec(9 \frac{\pi}{4} )$
​

Answer 1

Answer:

3

Step-by-step explanation:

Solution

(sinπ9)(4+secπ9)

=sin20∘(4+1cos20∘)

=4sin20∘cos20∘+sin20∘cos20∘

=2sin40∘+sin20∘cos20∘

=(sin40∘+sin40∘+sin20∘cos20∘

sin40∘+2sin30∘cos10∘cos20∘

=sin40∘+cos10∘cos20∘

=cos50∘+cos10∘cos20∘

=2cos30∘cos20∘cos20∘

=3–√