Home
Class 9
MATHS
Solve for x : cos^(2)30^(@)+sin^(2)2x=...

Solve for x :
`cos^(2)30^(@)+sin^(2)2x=1`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equation \( \cos^2(30^\circ) + \sin^2(2x) = 1 \), we can follow these steps: ### Step 1: Calculate \( \cos^2(30^\circ) \) We know that: \[ \cos(30^\circ) = \frac{\sqrt{3}}{2} \] Thus, \[ \cos^2(30^\circ) = \left(\frac{\sqrt{3}}{2}\right)^2 = \frac{3}{4} \] ### Step 2: Substitute \( \cos^2(30^\circ) \) into the equation Now, substitute \( \cos^2(30^\circ) \) into the original equation: \[ \frac{3}{4} + \sin^2(2x) = 1 \] ### Step 3: Isolate \( \sin^2(2x) \) Subtract \( \frac{3}{4} \) from both sides: \[ \sin^2(2x) = 1 - \frac{3}{4} \] \[ \sin^2(2x) = \frac{1}{4} \] ### Step 4: Take the square root of both sides Taking the square root gives us: \[ \sin(2x) = \frac{1}{2} \quad \text{or} \quad \sin(2x) = -\frac{1}{2} \] ### Step 5: Solve for \( 2x \) 1. For \( \sin(2x) = \frac{1}{2} \): \[ 2x = 30^\circ + n \cdot 360^\circ \quad \text{or} \quad 2x = 150^\circ + n \cdot 360^\circ \] where \( n \) is any integer. 2. For \( \sin(2x) = -\frac{1}{2} \): \[ 2x = 210^\circ + n \cdot 360^\circ \quad \text{or} \quad 2x = 330^\circ + n \cdot 360^\circ \] ### Step 6: Solve for \( x \) Now, divide all equations by 2: 1. From \( 2x = 30^\circ \): \[ x = 15^\circ \] 2. From \( 2x = 150^\circ \): \[ x = 75^\circ \] 3. From \( 2x = 210^\circ \): \[ x = 105^\circ \] 4. From \( 2x = 330^\circ \): \[ x = 165^\circ \] ### Final Solutions Thus, the possible values of \( x \) are: \[ x = 15^\circ, 75^\circ, 105^\circ, 165^\circ \]
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRICAL RATIOS OF STANDARD ANGLES

    ICSE|Exercise EXERCISE 23(B)|34 Videos
  • TRIGONOMETRICAL RATIOS

    ICSE|Exercise EXERCISE 22(B)|50 Videos
  • TRIGONOMETRY

    ICSE|Exercise TOPIC -4 ( COMPLEMENTARY ANGLES ) (4 MARKS QUESTIONS )|4 Videos

Similar Questions

Explore conceptually related problems

Solve for x : cos^(2)30^(@)+cos^(2)x=1

Solve for x : cos(2x-30^(@))=0

Solve for x : sin^(2)60^(@)+cos^(2)(3x-9^(@))=1

Solve for x : sin^(2)x+sin^(2)30^(@)=1

Solve for x : sin(x+10^(@))=1/2

Solve for x : cos(2sin^(-1)x)=1/3

Solve for x : (i) cos((x)/(2) + 10^(@)) = (sqrt(3))/(2) (ii) sin^(2) 60^(@) + cos^(2)(3x - 9^(@)) = 1

Solve for x, where 0 le x le 90^(@) sin^(2) x + cos^(2) 30^(@) = (5)/(4)

Solve 4 cos^(2)x+6 sin^(2)x=5 .

Solve for x : sin^(- 1)(sin((2x^2+4)/(1+x^2)))lt pi-3

ICSE-TRIGONOMETRICAL RATIOS OF STANDARD ANGLES-EXERCISE 23(C)
  1. Solve for x : sin^(2)x+sin^(2)30^(@)=1

    Text Solution

    |

  2. Solve for x : cos^(2)30^(@)+cos^(2)x=1

    Text Solution

    |

  3. Solve for x : cos^(2)30^(@)+sin^(2)2x=1

    Text Solution

    |

  4. Solve for x : sin^(2)60^(@)+cos^(2)(3x-9^(@))=1

    Text Solution

    |

  5. If 4cos^(2)x=3 and x is an acute angle, find the value of : x

    Text Solution

    |

  6. If 4cos^(2)x=3 and x is an acute angle, find the value of : cos^(2)x...

    Text Solution

    |

  7. If 4cos^(2)x=3 and x is an acute angle, find the value of : cos3x

    Text Solution

    |

  8. If 4cos^(2)x=3 and x is an acute angle, find the value of : sin2x

    Text Solution

    |

  9. In DeltaABC, angleB=90^@), AB=y" units", BC=sqrt(3) " units", AC = 2 u...

    Text Solution

    |

  10. In DeltaABC, angleB=90^@), AB=y" units", BC=sqrt(3) " units", AC = 2 u...

    Text Solution

    |

  11. In DeltaABC, angleB=90^@), AB=y" units", BC=sqrt(3) " units", AC = 2 u...

    Text Solution

    |

  12. In DeltaABC, angleB=90^@), AB=y" units", BC=sqrt(3) " units", AC = 2 u...

    Text Solution

    |

  13. If 2cos(A+B)=2sin(A-B)=1, find the values of A and B.

    Text Solution

    |

  14. Solve the following equations for A, if : 2sinA=1

    Text Solution

    |

  15. Solve the following equations for A, if : 2cos2A=1

    Text Solution

    |

  16. Solve the following equations for A, if : sin3A=sqrt(3)/2

    Text Solution

    |

  17. Solve the following equations for A, if : sec2A=2

    Text Solution

    |

  18. Solve the following equations for A, if : sqrt(3)tanA=1

    Text Solution

    |

  19. Solve the following equations for A, if : tan3A=1

    Text Solution

    |

  20. Solve the following equations for A, if : 2sin3A=1

    Text Solution

    |