If sin A + sin2A = 1  then what is the value of cos2A + cos4

Subject

Quantitative Aptitude

Class

SSCCGL Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

A can do a piece of work in 8 days and B can do it in 10 days separately. How many days would it take for both A and B to finish the same work together?

  • 33 over 8

  • 40 over 9

  • 41 over 10

  • 42 over 11


52.

The lengths of the diagonal of a rhombus are 8cm and 6 cm. The area of rhombus is:

  • 96 cm2

  • 60 cm2

  • 48 cm2

  • 24 cm2


53.

Two successive discounts of 10% and 20% are equivalent to a single discount of

  • 28%

  • 27%

  • 25%

  • 30%


54.

A and B together have Rs 6,300/-. If 5 over 19 of A's income is equal to 2 over 5 of B's amount. The amount of B is

  • Rs 2,500

  • Rs 3,800

  • Rs 2,300

  • Rs 4,000


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55.

If the selling price of 40 articles is equal to the cost price of 50 articles, the loss or gain percent is

  • 25% gain

  • 20% gain

  • 25% loss

  • 20% loss


56.

A's income is 25% more than B's income. B's income is what percent of A's income?

  • 80%

  • 75%

  • 50%

  • 25%


57.

In what time will a train, 60m long, running at the rate of 36 km/h pass a telegraph post?

  • 9 sec

  • 8 sec

  • 7 sec

  • 6 sec


58.

If 5 straight x space plus space 1 over straight x space equals space 10 comma then straight x squared space plus space fraction numerator 1 over denominator 25 straight x squared end fraction is equal to

  • 2 1 fifth

  • 3 1 fifth

  • 3 3 over 5

  • 2 3 over 5


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59.

If 4 straight r space equals space straight h space plus space square root of straight r squared plus straight h squared end root  then r : h is left parenthesis straight r not equal to 0 right parenthesis

  • 17 : 8

  • 8 : 17

  • 8 : 15

  • 15 : 8


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60.

If sin A + sin2A = 1  then what is the value of cos2A + cos4A?

  • 1

  • 2

  • 1/2

  • 1/4


A.

1

sin A + sin2A = 1
       sin A = 1 - sin2A
       sin A = cos2A
∴  cos2A + cos4A = sin A + sin2A = 1


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