- From outside, trigonometry may look lengthy, boring, difficult, tedious and frustrating. But it doesn’t change the fact that trigonometry as a topic important for SSC exams (CGL, FCI, CPIO etc.) and CDS exam (Combined defense services).
- In CGL-2012, at both Tier I and II, there were around 8 questions from Trigonometry alone.
- Based on the previous SSC papers, I classify the Trigonometry questions mainly into 4 types
|1. Height and distance related||
|2. Table related||
|3. Complementary angles (90-A) related||
|4. Combo of Trigonometry formulas + Algebra formulas.||
Let’s start with the first type: Height and Distance related.
These questions can be further classified into five types
|1. One building one angle||From a ground point that is 400 meters away from a building, the angle of elevation is 30 degrees. Find height of this building.|
|2. Broken trees and telephone poles||A tree breaks down due to storm and its top touches the ground and makes an angle of 30°. If the top of that tree touches the ground 15 m away from the bottom then find the height of this tree|
|3. One building two angles or two shadows.||As angle of elevation of the sun increases from 30° to 60°, Shadow of a building is reduced by 10 m find the height of this building.|
|4. Two buildings two angles||From a 60 m tall building, the angle of depression of the top and the bottom of a tower is 30 and 60° respectively. Find the height of this tower.|
|5. Find Speed time or distance.||A man on the top of building observes a car moving at a uniform speed and coming directly towards the building. It takes 12 minutes for the angle of depression to change from 30 to 45, how soon after this, will the car reach the building?|
In the books, you may have seen a big table containing values of sin cos tan cosec sec and cot for 0, 30, 45, 60 and 90 angles. As far as Height and distance is concerned, there is absolutely no need to mugup that big n boring table because of following reasons
- Most of the questions only have 30, 45 and 60 degrees.
- And To memorize the values of SIN, COS, TAN, COSEC, SEC and COT for 30, 45, 60, Just remember the Topi TrianglesTM technique. (Explained in following video)
If the video is not visible, check it directly on my youtube channel youtube.com/user/TheMrunalPatel
Above video also contains overview of the Height and Distance Questions and its five subtypes. How to solve each type of height and distance questions, will be explained in depth in separate videos later on. For more [Aptitude] related content, visit the Archive on Mrunal.org/aptitude