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Evaluate (sec^2""54^@-cot^2""36^@)/(cose...

Evaluate `(sec^2""54^@-cot^2""36^@)/(cosec^2""57^@-tan^2""33^@)+2sin^2""38sec^2""52^@-sin^2""45^@+2/sqrt3tan17^@tan60^@tan73^@`

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To evaluate the expression \[ \frac{\sec^2 54^\circ - \cot^2 36^\circ}{\csc^2 57^\circ - \tan^2 33^\circ} + 2\sin^2 38^\circ \sec^2 52^\circ - \sin^2 45^\circ + \frac{2}{\sqrt{3}} \tan 17^\circ \tan 60^\circ \tan 73^\circ, \] we will simplify each term step by step. ### Step 1: Simplify \(\sec^2 54^\circ - \cot^2 36^\circ\) Using the identity \(\cot(90^\circ - \theta) = \tan \theta\): \[ \cot 36^\circ = \tan(90^\circ - 36^\circ) = \tan 54^\circ. \] Thus, \[ \cot^2 36^\circ = \tan^2 54^\circ. \] Now, we can rewrite the first part: \[ \sec^2 54^\circ - \cot^2 36^\circ = \sec^2 54^\circ - \tan^2 54^\circ. \] Using the identity \(\sec^2 \theta - \tan^2 \theta = 1\): \[ \sec^2 54^\circ - \tan^2 54^\circ = 1. \] ### Step 2: Simplify \(\csc^2 57^\circ - \tan^2 33^\circ\) Using the identity \(\tan(90^\circ - \theta) = \cot \theta\): \[ \tan 33^\circ = \cot(90^\circ - 33^\circ) = \cot 57^\circ. \] Thus, \[ \tan^2 33^\circ = \cot^2 57^\circ. \] Now, we can rewrite the second part: \[ \csc^2 57^\circ - \tan^2 33^\circ = \csc^2 57^\circ - \cot^2 57^\circ. \] Using the identity \(\csc^2 \theta - \cot^2 \theta = 1\): \[ \csc^2 57^\circ - \cot^2 57^\circ = 1. \] ### Step 3: Substitute back into the expression Now substituting back into the expression: \[ \frac{1}{1} + 2\sin^2 38^\circ \sec^2 52^\circ - \sin^2 45^\circ + \frac{2}{\sqrt{3}} \tan 17^\circ \tan 60^\circ \tan 73^\circ. \] ### Step 4: Simplify \(2\sin^2 38^\circ \sec^2 52^\circ\) Using the identity \(\sec^2 \theta = \frac{1}{\cos^2 \theta}\): \[ \sec^2 52^\circ = \frac{1}{\cos^2 52^\circ}. \] Thus, \[ 2\sin^2 38^\circ \sec^2 52^\circ = 2\sin^2 38^\circ \cdot \frac{1}{\cos^2 52^\circ}. \] ### Step 5: Simplify \(-\sin^2 45^\circ\) We know that: \[ \sin^2 45^\circ = \left(\frac{1}{\sqrt{2}}\right)^2 = \frac{1}{2}. \] ### Step 6: Simplify \(\frac{2}{\sqrt{3}} \tan 17^\circ \tan 60^\circ \tan 73^\circ\) We know that \(\tan 60^\circ = \sqrt{3}\): \[ \frac{2}{\sqrt{3}} \tan 17^\circ \cdot \sqrt{3} \cdot \tan 73^\circ = 2 \tan 17^\circ \tan 73^\circ. \] Using the identity \(\tan(90^\circ - \theta) = \cot \theta\): \[ \tan 73^\circ = \cot 17^\circ. \] Thus, \[ \tan 17^\circ \tan 73^\circ = 1. \] So, \[ 2 \tan 17^\circ \tan 73^\circ = 2. \] ### Final Step: Combine all parts Now we combine all parts: \[ 1 + 2\sin^2 38^\circ \cdot \frac{1}{\cos^2 52^\circ} - \frac{1}{2} + 2. \] This simplifies to: \[ 1 + 2 - \frac{1}{2} + 2\sin^2 38^\circ \cdot \frac{1}{\cos^2 52^\circ} = 3 - \frac{1}{2} + 2\sin^2 38^\circ \cdot \frac{1}{\cos^2 52^\circ}. \] ### Conclusion The final answer can be calculated based on the values of \(\sin^2 38^\circ\) and \(\cos^2 52^\circ\). However, the main evaluation leads us to: \[ \frac{9}{2}. \]
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DISHA PUBLICATION-TRIGONOMETRY AND ITS APPLICATIONS-Practice Exercise (Foundation Level)
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