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The value of the expression $cos^2 45° + cos^2 135° + cos^2 225° + cos^2 315°$ is: |
2 $\frac{1}{2}$ $\frac{2}{3}$ 1 |
2 |
cos² 45° + cos² 135° + cos² 225° + cos² 315° = cos² 45° + cos² ( 90° + 45° ) + cos² ( 180° + 45° ) + cos² ( 360° - 45° ) = cos² 45° +( - sin 45°) + (- cos45°)² + cos² 45° = \(\frac{1}{2}\) + \(\frac{1}{2}\) + \(\frac{1}{2}\) + \(\frac{1}{2}\) = 2 |
