Sponsor Area

Some Applications Of Trigonometry

Question
CBSEENMA10007939

Evaluate:
cos 30°. cos 45° - sin 30°. sin 45°

Solution
cos 30°. cos 45° - sin 30°. sin 45°
                       = fraction numerator square root of 3 over denominator 2 end fraction cross times fraction numerator 1 over denominator square root of 2 end fraction minus 1 half cross times fraction numerator 1 over denominator square root of 2 end fraction
equals space fraction numerator square root of 3 over denominator 2 square root of 2 end fraction minus fraction numerator 1 over denominator 2 square root of 2 end fraction space equals space fraction numerator square root of 3 minus 1 over denominator 2 square root of 2 end fraction cross times fraction numerator square root of 2 over denominator square root of 2 end fraction
equals space fraction numerator square root of 6 minus square root of 2 over denominator 4 end fraction.