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Find the value of (cos^(2)20^(@)+cos^(2)...

Find the value of `(cos^(2)20^(@)+cos^(2)70^(@))/(sin^(2)59^(@)+sin^(2)31^(@))`.

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To solve the expression \((\cos^2 20^\circ + \cos^2 70^\circ) / (\sin^2 59^\circ + \sin^2 31^\circ)\), we can follow these steps: ### Step 1: Simplify the numerator We start with the numerator \(\cos^2 20^\circ + \cos^2 70^\circ\). Using the identity \(\cos(90^\circ - \theta) = \sin \theta\), we can express \(\cos^2 70^\circ\) as: \[ \cos^2 70^\circ = \sin^2(90^\circ - 70^\circ) = \sin^2 20^\circ \] Thus, the numerator becomes: \[ \cos^2 20^\circ + \sin^2 20^\circ \] ### Step 2: Apply the Pythagorean identity Using the Pythagorean identity \(\cos^2 \theta + \sin^2 \theta = 1\), we have: \[ \cos^2 20^\circ + \sin^2 20^\circ = 1 \] ### Step 3: Simplify the denominator Now, we simplify the denominator \(\sin^2 59^\circ + \sin^2 31^\circ\). Using the identity \(\sin(90^\circ - \theta) = \cos \theta\), we can express \(\sin^2 31^\circ\) as: \[ \sin^2 31^\circ = \cos^2(90^\circ - 31^\circ) = \cos^2 59^\circ \] Thus, the denominator becomes: \[ \sin^2 59^\circ + \cos^2 59^\circ \] ### Step 4: Apply the Pythagorean identity to the denominator Using the Pythagorean identity again, we have: \[ \sin^2 59^\circ + \cos^2 59^\circ = 1 \] ### Step 5: Combine the results Now we can substitute back into our original expression: \[ \frac{\cos^2 20^\circ + \cos^2 70^\circ}{\sin^2 59^\circ + \sin^2 31^\circ} = \frac{1}{1} = 1 \] ### Final Answer Thus, the value of the expression is: \[ \boxed{1} \]
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