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Cos² 2x = (1+cos 4x )/2
cos² 6x = (1+cos 12x)/2
subtract to get 1/2 (cos 4x - cos 12x )
= 1/2 (2 sin 4x sin 8x ) as cos A - cos B = 2 [ sin (A+B)/2 sin (A-B)/2 ]
so the answer
Answer:
Question A is D and Question B is B
Answer: √117
Step-by-step explanation:
Since no diagram present, am assuming hypotenuse AB and right angle C. Let side opp angle B be b, and side opposite angle A be a. Altitude CD is x.
a^2 + b^2 = 22^2 (Pythagorean)
Using Pythag on two smaller triangles,
x^2 + 13^2 = a^2
x^2 + 9^2 = b^2
Substituting in first equation,
x^2 + 13^2 + x^2 + 9^2 = 22^2
x^2 = 117, so x = √117
