What is the value of :1 + cosπ81 + cos3&pi

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

61.

If  A = cos12° - cos36°sin96° + sin24° and B = sin60° - sin12°cos48° - cos72°, then what is AB = ?

  •  - 1

  • 0

  • 1

  • 2


62.

sinA + sin2A + sin3A is equal to which of thfollowing ?

1. 4sin2Acos2A2

2. 2sin2AsinA2 + cosA22

3. 8sinAcosAcos2A2

  • 1 and 2 only

  • 2 and 3 only

  • 1 and 3 only

  • 1, 2 and 3


63.

If x = sin70° . sin50° and y = cos60° . cos80°, then what is xy = ?

  • 116

  • 18

  • 14

  • 12


64.

If sinθ1 + sinθ2 + sinθ3 + sinθ4 = 4, then what is the value of :

cosθ1 + cosθ2 + cosθ3 + cosθ4 ?

 

  • 0

  • 1

  • 2

  • 4


Advertisement
Advertisement

65.

What is the value of :

1 + cosπ81 + cos3π81 + cos5π81 + cos7π8 ?

  • 12

  • 12 + 122

  • 12 - 122

  • 18


D.

18

 cos3π8 = cosπ2 - π8 = sinπ8     cos5π8 = cosπ2 + π8 = - sinπ8         cos7π8 = cosπ - π8 =  - cosπ81 + cosπ81 + cos3π81 + cos5π81 + cos7π8= 1 + cosπ81 +  sinπ81 - sinπ81 - cosπ8= 1 - cos2π81 - sin2π8= sin2π8cos2π8= 142sinπ8cosπ82= 14sinπ42 = 14122 = 18


Advertisement
66.

If xcosθ + ysinθ = z, then what is the value of

xsinθ - ycosθ2 ?

  • x2 + y2 - z2

  • x2 - y2 - z2

  • x2 - y2 + z2

  • x2 + y2 + z2


67.

If A = x   : x2 + 6x - 7 < 0 and B = x   : x2 + 9x + 14 > 0,

then which of the following is/are correct ?

1. A  B = x  R : - 2 < x < 12. AB = x R : - 7 < x < - 2

Select the correct answer using the code given below :

  • 1 only

  • 2 only

  • both 1 and 2

  • neither 1 nor 2


68.

If sin18° = 5 - 14, then what is the value of sin 81° ?

  • 3 + 5 + 5 - 54

  • 3 +5 + 5 + 54

  • 3 -5 + 5 - 54

  • 3 +5 - 5 - 54


Advertisement
69.

What is 1 - tan2° . cot62°tan152° - cot88° = ?

  • 3

  • - 3

  • 2 - 1

  • 1 - 2


70.

What is tan25°tan15° + tan15°tan50° + tan25°tan50° = ?

  • 0

  • 1

  • 2

  • 4


Advertisement