Question

value cos 15 + cos 105​

Answer 1

Step-by-step explanation:

$\cos(15) + \cos(105) \\ \\ \\ = 2 \cos( \frac{15 + 105}{2} ) \cos( \frac{105 - 15}{2} ) \\ \\ \\ = 2 \cos(60) \cos(45) \\ \\ \\ = 2 \times \frac{1}{2} \times \frac {1}{\sqrt {2}}\\ \\ \\ =\frac {1}{\sqrt {2}}$

Answer 2

Answer:

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=cos(15)+cos(105)

=2cos(15+105)cos(105-15)

2 2

=2cos(60)(45)

=2×1×1

2 /2

= 1

/2

so,the ANSWER is 1 upon root 2.