Trigonometry Practice Test 1

Question : 33 of 40

Marks: +1, -0

The value of cos105° + sin105° is:

Solution:

cos105° + sin105°
= cos(60° + 45°) + sin(60° + 45°)
= cos60° cos45° – sin60° sin45° + sin60° cos45° + cos60° sin45°

=1/2 . 1/√2 -√3/2 . 1/√2

+√3/2 . 1/√2 +1/2 . 1/√2

=2/{2√2}=1/√2

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