Trigonometry Shortcut Tricks for SSC CGL Exam

In this post, we are sharing an important Trigonometry Shortcut Trick using which, you would be able to solve a typical trigonometry question within few seconds.

Typical Questions with which this trick Works

1. Find the value of Sin21+Sin23 + Sin25+ Sin27...........Sin289
2. Find the value of Sin22+Sin24 + Sin26+ Sin28...........Sin288
This kind of questions are always asked in SSC CGL Exam. Normally, your solution include: finding the number of terms using AP formula and then applying your mind right?. This method however is a bit lengthy and consumes more than 2 minutes.

In this post, We will explain you an easy method for solving this kind of question. So, Are you ready?

Steps Involved in Shortcut Method

Step-1 : Finding the total Number of terms
Don't panic. We are not going to tell you the same thing i.e find the number of terms using the A.P formula. Instead, we are providing you an easy formula for finding the number of terms.

No. of Terms = [(Last term - First Term)/Common Difference] +1

If you have managed to find the total number of terms, it will take no time in finding your answer. The formula for finding the answer is :

Answer = No. of Terms /  2

That's it guys. Isn't that simple? Now I will explain the same through examples:

Examples with Explanation
Q1.Find the value of Sin21+Sin23 + Sin25+ Sin27...........Sin289
Sol : Total Number of Terms = [(Last term - First Term)/Common Difference] +1
= [(89- 1)/ 2] +1  = 45
Answer =  No. of Terms /  2  = 45/2

Q2.Find the value of Sin22+Sin24 + Sin26+ Sin28...........Sin288
Sol : Total Number of Terms = [(Last term - First Term)/Common Difference] +1
= [(88- 2)/ 2] +1  =44
Answer =  No. of Terms /  2  = 44/2 =22

Similarly, you can solve all questions of this kind. For practice, try solving the below given questions yourself:
1. Find the value of Sin213+Sin215 + Sin217+ Sin219...........Sin277
2. Find the value of Sin217+Sin219 + Sin221+ Sin223...........Sin275

If you have any doubt or question, feel free to ask the same through below given comment form.