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How do you evaluate #\sin 80^ { \circ } \sec 10^ { \circ }#?

Answer 1

Aaliyah Abdullah

#=1 #

Use #cos(90^circ - theta^circ ) = sin (theta^circ ) #

let #theta = 80^circ #

#=> cos(10^circ) = sin(80^circ) #

The question asks for:

#sin(80^circ) * 1/(cos(10^circ)) #

#=> sin(80^circ) * 1/ sin(80^circ) #

#= 1 #

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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