Question #a1332

1 Answer
sjc
Jan 26, 2018

#sec(145)=-1.2208#

Explanation:

since#" " secx= 1/cosx#

we will find #" "cos145# and return to #" "sec145 # at the end.

#cos145#

#145^0# is in the second quadrant.

cosine is negative in the second quadrant

#:.cos145=-cos35#

from calculator and working to 4 dps

cos 35=0.8192

#:.cos145=-0.8192#

#sec145=1/cos145=1/(-0.8192)#

#=-1.2208#

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