Answered

Solve the following equation for 0° ≤ θ < 360°. Use the "^" key on the keyboard to indicate an exponent. For example, sin2x would be typed as sin^2x. Be sure to show all your work.

2sin2x - cos2 x - 2 = 0

Answer :

InesWalston

Answer-

[tex]\boxed{\boxed{x=90^{\circ},270^{\circ}}}[/tex]

Solution-

The given equation-

[tex]\Rightarrow 2\sin^2 x-\cos^2 x-2=0[/tex]

As

[tex]\sin^2 x+\cos^2 x=1\ \ \Rightarrow \cos^2 x=1-\sin^2 x[/tex]

Putting this,

[tex]\Rightarrow 2\sin^2 x-(1-\sin^2 x)-2=0[/tex]

[tex]\Rightarrow 2\sin^2 x-1+\sin^2 x-2=0[/tex]

[tex]\Rightarrow 3\sin^2 x-3=0[/tex]

[tex]\Rightarrow 3\sin^2 x=3[/tex]

[tex]\Rightarrow \sin^2 x=1[/tex]

[tex]\Rightarrow \sin x=\sqrt1[/tex]

[tex]\Rightarrow \sin x=\pm 1[/tex]

[tex]\Rightarrow \sin x=1,\ \sin x=-1[/tex]

[tex]\Rightarrow x=\sin^{-1}(1),\ x=\sin^{-1}(-1)[/tex]

[tex]\Rightarrow x=90^{\circ}+n360^{\circ},\ x=270^{\circ}+n360^{\circ}[/tex]

Where n=0, 1, 2, ......

As given 0° ≤ x < 360°, so putting n = 0

[tex]\Rightarrow x=90^{\circ},\ x=270^{\circ}[/tex]


This is the guy aboves work, I just wrote it out so you can copy and paste easier.

2sin^2x-cos^2x-2=0

sin^2x+cos^2x=1

cos^2x=1-sin^2x

2sin^2x-(1-sin^2x)-2=0

2sin^2x -1 +sin^2x-2=0

3sin^2x-3=0

3sin^2x=3

sin^2x=1

sin x =(sqr root)1

sin x= + or - 1

sin x =1    sin x = -1

x= sin^-1(1)   x=sin^-1 (-1)

x=90+n360    x=270 + 360n

x=90, 270 (wrote down so it stands out more)

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