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Evaluate : 3 cos 80^(@)cosec 10^(@)+2s...

Evaluate :
`3 cos 80^(@)cosec 10^(@)+2sin 59^(@)sec 31^(@)`

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The correct Answer is:
To evaluate the expression \( 3 \cos 80^\circ \csc 10^\circ + 2 \sin 59^\circ \sec 31^\circ \), we can follow these steps: ### Step 1: Use Trigonometric Identities We know from trigonometric identities that: - \( \sin(90^\circ - \theta) = \cos(\theta) \) - \( \cos(90^\circ - \theta) = \sin(\theta) \) ### Step 2: Rewrite \( \cos 80^\circ \) and \( \sin 59^\circ \) Using the above identities: - \( \cos 80^\circ = \sin(90^\circ - 80^\circ) = \sin 10^\circ \) - \( \sin 59^\circ = \cos(90^\circ - 59^\circ) = \cos 31^\circ \) ### Step 3: Substitute in the Expression Now substitute these values back into the expression: \[ 3 \cos 80^\circ \csc 10^\circ + 2 \sin 59^\circ \sec 31^\circ = 3 \sin 10^\circ \csc 10^\circ + 2 \cos 31^\circ \sec 31^\circ \] ### Step 4: Simplify Using Definitions Recall that: - \( \csc \theta = \frac{1}{\sin \theta} \) - \( \sec \theta = \frac{1}{\cos \theta} \) Thus: - \( \sin 10^\circ \csc 10^\circ = \sin 10^\circ \cdot \frac{1}{\sin 10^\circ} = 1 \) - \( \cos 31^\circ \sec 31^\circ = \cos 31^\circ \cdot \frac{1}{\cos 31^\circ} = 1 \) ### Step 5: Substitute Back into the Expression Now substitute these results back into the expression: \[ 3 \cdot 1 + 2 \cdot 1 = 3 + 2 = 5 \] ### Final Answer Thus, the evaluated result is: \[ \boxed{5} \]
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