What is the value of $${\sqrt{1-cosA\over{1+cosA}}}$$?

Five years ago the sum of the ages of A and B was 58 years. The difference between B's age 8 years ago and A's age 8 years hence is 16 years. The ratio of the present ages of A and B is:

A speaks the truth 5 out of 7 times and B speaks truth 8 out of 9 times. What is the probability that they contradict each other in stating the same fact?

Study the following graph carefully to answer the given questions

 T and V started the work. After 3 days Z joined them, who can complete alone the same whole work in 3 days. What is the total number of days in which they had completed the work?

The average temperature of Monday, Tuesday, Wednesday and Thursday is 60°. The average temperature for Tuesday, Wednesday, Thursday and Friday is 63°. If the ratio of temperature for Monday and Friday is 21 : 25, then what is the temperature of Friday ? 

In a two - digit number, the digit at the unit's place is 1 less than twice the digit at the ten's place. If the digits at units and ten's place are interchanged, the difference between the new and the original number is less than the original number by 20. The original number is: 

Mr. Rajesh invested Rs.25000 in two fixed deposits X and Y offering compound interest at 6% per annum and 8% per annum, respectively. If the total amount of interest accrued in two years through both fixed deposits is Rs.3518, then the amount invested in scheme X is -

If $$ {x^4}+{1\over{x^4}}$$ then find $$ {x^3}-{1\over{x^3}}=?$$