Question
If cos 39° = x/ √(x2 + y2),
then the value of tan 51° = ?Solution
cos 39° = x/ √(x 2 + y 2) = Base/hypotenuse So base = x & hypotenuse =
so perpendicular = y But for angle 51° which is complimentary of 39° , perpendicular =y & base = x. So tan 51° = base/perpendicular =
Alternate Method : cos 39° =
OR sin (90°-39°) =
OR sin 51° =
-----(1) Squaring on both sides, we will get, sin2 51° =
or 1 - cos2 51° =
or cos2 51° = 1 -
=
So cos 51° =
----(2) Hence tan 51° = sin51°/ cos51° =

Two numbers are in the ratio of 6:13. If three is added to both numbers, the ratio becomes 1:2. Find the smaller number.
Divide Rs. 2541 among Deepa and Deepak in the ratio (11/8) : (11/6) ?
Find the fourth proportion of (k + 2), (2k), and (3k + 6). (Note: 'k' is the smallest two-digit prime number.)
If 'A' = (2/5) of 'B', 'B' = (3/4) of 'C', then find the value of (A + B) :(B + C) .
The sum of the first, second, and third numbers is 231. The first and second numbers are in a 3:5 ratio, and the second and third...
Mahika distributed 800 chocolates among A, B and C. A got 50% more chocolates than B and 60% less chocolates than C. How many chocolates did C receive? ...
A container holds 180 litres of a milk and water mixture, where the amount of milk exceeds the amount of water by 44 litres. If 8 litres of milk and 12 ...
What is the fourth proportional to 5, 9, 25?
The sum of three numbers is 147. If the ratio of the first to the second is 2:3 and that of second to the third is 5:8 then the second number is?
The ratio of the incomes of Vineet and Vidya is 12:5 respectively. Vineet saves 25% of his income while Vidya saves 20% of his income. The sum of their...