The value of the expression (cos^{2} 23^{0} - sin^{2} 67^{0}) is positive.

False

cos^{2} 23° - sin^{2} 67° =(cos 23°+sin 67°)(cos 23°-sin 67°)

(∵(a^{2}-b^{2}) = (a+b)(a-b))

= [cos 23°+sin(90°-23°)] [cos 23°-sin(90°-23°)]

= (cos 23°+cos 23°)(cos 23°-cos 23°) (∵sin(90°-θ) = cos θ)

= (cos 23°+cos 23°).0

= 0, which is neither positive nor negative

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