- Introduction: Trigonometry Speed Time Distance
- Approach:Trigonometry Speed Time Distance
- Mock questions

# Introduction

Continuing in the series of “Trigonometry –>Height and Distance(HnD)–> Five types of Questions.

5^{th} and the last type of question is “finding speed, time or distance”. Here are example questions (both solved in the video)

- A jet is flying at a constant height of 4500 root 3meters. Angle of elevation of the jet from a point on ground is 60 Degrees. After 30 seconds of flight, this angle becomes 30 degrees. Find speed of this jet plane.
- A car is 60m away from a building. Angle of elevation is 45. After 5 seconds, car moves away from the building and angle is decreased to 30. Find speed of this car.

# Approach

- Basically approach is same as “one building two angles” type of questions.= Since two angles are given, you make two equations of “TAN” using
*Topi-triangle shortcut*and you get a distance.^{TM} - Then apply “STD” formula (speed x time = distance) and you’ll get the answer.
- Check the following video to see it in detail and after watching the video, solve the mock questions given at the bottom of this article.

If the video is not visible, check it directly on youtube by clicking me

# Mock questions

- A 1.3 m tall man spots a balloon moving with the wind in a horizontal line at a constant height of 91.3 m above the ground. The angle of elevation of this balloon is 60°. After some time the angle is reduced to 30°. Find the distance travelled by the balloon during this interval
- From a 100m tall lighthouse, the angle of depression of a ship is 30. After some time, angle of depression increases to 45. Find the distance travelled by ship during this time interval. (hint: STD formula unnecessary here!)
- 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?

## Answers

- 60 root 3 OR 103.8m
- 73m
- 16.38 minutes

For more [Aptitude] related content, visit the Archive on Mrunal.org/aptitude

Natasha22/03/2013 at 8:30 amthanks a lot sir………………

Abhi28/06/2013 at 11:39 pmIts really very conceptual.thanks a lot

TARUN13/03/2014 at 7:22 pmThamks a lot sir… All articles r verry useful…

In this article, i hv some difficulty in mock questions 1 and 3.. so plz help me for sollution…

Thanks..

vandy30/04/2014 at 10:21 pma man cover 2/5 of journey in 1 hr, and 1/5 of journey in 1 hr and 45 min to cover remaining 220km. find total dist.

zain14/07/2014 at 4:54 amIt is so awesome and useful

Because i need some airplanes knowledge so

ThAnKs

kavita23/08/2014 at 12:40 pmplz kuch videos quantitude aptitude p free of cost provide kr dijiye

Manu Reddy10/09/2014 at 8:18 amSir, could you explain 3rd question.

deepak03/08/2015 at 6:04 amleft out time for the exam is 6 days in hand,can i have a fast track revision from topic 1 to last topic…

Aspirant18/02/2016 at 1:13 pmcan any1 please show the steps for 3rd problem in the mock test?

Sourin Gorai19/04/2016 at 3:46 pmPlease tell me the age limit of OBC candidate?