Trigonometry Part-1

Trigonometry is yet another scoring section of CGL. Most questions can be resolved with Jugad.

Like algebra, where we considered the values ​​of the variable, in the trigonometry we would consider the value of 'live'. And just like algebra, make sure that the value you are assuming for the target will not be denominator zero.
How to value -
1. When you do not have to deal with the differences then you can say Θ = 90 or 0
Like (acosΘ - bsinΘ)
2. So when is the numerator and Θ = 90 or 0 enter denominator remains zero, you can go with Θ = 45.
3. Do not assume value for Gita, on which the trigonometric function is not defined. As when tan is given, you can not accept Θ = 9 0.
4. When you consider two angles, go with A = 60 and B = 30
Note: These are not hard and fast rules and you can assume your preferred value, but make sure denominator ≠ 0. Sometimes when you consider ass, you ended up with two options (A and B say) Those who are giving similar results (but two options will still end, i.e., C and D) Now change the value of Directa and check only A and B.

You only have to remember the values ​​of sin, anguish and tan (Θ = 0, 30, 45 and 60). The value of kausak, sek and coat can be obtained by mutually receiving sin, kos and tan respectively.
Solve CGL questions now

Q. 1.

let Θ = 9 0
X = A (1 + 0) = A
Y = B (1 - 0) = B
Then x2 / a2 + y2 / b2 = 2
Answer: C

Some complex questions can be solved by considering the value of the goat
Q. 2.

Then say Θ = 0
Then a * 1 + b * 0 = core A = C
You will get the value of acosΘ - bsin होगा
acosΘ - bsinΘ = -b (since Θ = 9 0)
Now put a = c in all 4 options so that it can check which '-b' can be output as
Answer: D

Q. 3

Let Θ = 45
One (tan45 + cot45) = 1
So a = 1/2
sin45 + cos45 = b
Then b = √2
Take a = 1/2 and b = √2 all the options and check to see what's right in 4 equations (ie LHS should equal RHS)
Answer: A (LHS and RHS both equal 1)

Let Θ = 45
(TanA - secA - 1) / (tanA + secA + 1) = -√2 / (2 + √2) = -1 / (√2 + 1) = 1 - √2 (rational)
Place Θ = 45 in all 4 options and check which output will give (1 - √2) as
A) √2 - 1
B) √2 + 1
C) 1 - √2
D) √2 - 1
Answer: C

Sometimes you have to accept two angles

Q. 4

Let's do A = 60 and B = 30
Then N = 3 and M = √3
cos2a = 1/4 (since A = 60)
Now enter N = 3 and M = √3 in all the options and check which 1/4 will give
Answer: B


There is a type of question that is often asked by SSC -


Q. 5.

When you see secA + tanA = (let's say 'P') ... (1)
You can say, secA - tanA = 1 / p ... (2)
Add Now (1) and (2)
2secA = P + 1 / P
secA = (P2 + 1) / 2p [you can remember this formula]
tanA = (P2 - 1) / 2p

In the above question, P = 2
So secA = 5/4
Now we have to meet sina. The best way to determine the value of the trigonometric function is to create a triangle when the value of another function is given.
secΘ = Hypotenuse / Base
Here seca = 5/4, hence hypotenuse = 5 and base = 4, which means Vertical = 3
sinA = vertical / hypotenuse = 3/5 = 0.6
Answer: C