2 math questions please help


Answer:
Step-by-step explanation:
2)Cos²x - Sin² x = √2/2
Cos²x - Sin² x = Cos 2x
⇒ Cos 2x = √2/2
General solution for Cos 2x = √2/2 is
[tex]2x = \dfrac{\pi }{4}+2\pi n \ ; 2x=\dfrac{7\pi }{4}+2\pi n\\\\\\x = \dfrac{\pi }{2*4}+\dfrac{2\pi n }{2} \ ; \ x=\dfrac{7\pi }{4*2}+\dfrac{2\pi n}{2}\\\\\\x =\dfrac{\pi }{8}+\pi n ; \ x=\dfrac{7\pi }{8}+\pi n[/tex]
Option A
Answer:
See below for answers and explanations
Step-by-step explanation:
Problem 1
[tex]f(x)=5sin(\frac{x}{12})+14.5\\\\17=5sin(\frac{x}{12})+14.5\\ \\2.5=5sin(\frac{x}{12})\\ \\0.5=sin(\frac{x}{12})\\ \\\frac{x}{12}=\frac{\pi}{6}+2\pi n,\frac{5\pi}{6}+2\pi n\\ \\x=2\pi+24\pi n,10\pi+24\pi n[/tex]
Therefore, the fourth option is correct.
Problem 2
[tex]cos^2x-sin^2x=\frac{\sqrt{2}}{2}\\ \\cos(2x)=\frac{\sqrt{2}}{2}\\\\2x=\frac{\pi}{4}+2\pi n,\frac{7\pi}{4}+2\pi n\\ \\x=\frac{\pi}{8}+\pi n,\frac{7\pi}{8}+\pi n[/tex]
Therefore, the first option is correct.