Question

If x tan²120° + 4cos150° = 9, then x =​

Answer 1

Answer:

Hey mate, it is 4cos²150° not 4cos150°.

Step-by-step explanation:

tan²120°=tan²(90+30)°=cot²30°

cos²150°=cos²(90+60)°=sin²60°

Now,

in x tan²120° + 4cos²150° = 9,

putting the values we get:

xcot²30°+4sin²60°=9

⇒x(√3)²+4(√3/2)²=9

⇒3x+4*3/4=9

⇒3x+3=9

⇒3(x+1)=9

⇒x+1=9/3=3

⇒x=3-1

⇒x=2