Trigonometry

In this question sides and angles are measured

Transcript

00:00This is Unit 6, Trigonometry and Bearing, Exercise 6.5.

00:05The question is, Length of shadow of 10 meter high pole is 10 sqrt 3 meters.

00:11Find the angle of elevation of the sun.

00:13Aapke paas ek pole hai jo ke 10 meters uncha hai.

00:18BC is the height of a pole.

00:21Is pole ki wajah se shadow cast ho raha hai i.e. 10 sqrt 3 ye iska shadow ho gaya.

00:29We have to find the angle of elevation of the sun.

00:34Angle of elevation kya hota hai jab hum neeche khade hoke upar ki taraf dekhen to yaha pe

00:38humare paas aa jayega angle of elevation.

00:42We have to find, in this question we have to find the angle of elevation.

00:45Aap sabse pehle kya kaoge hai ki let alpha be the angle of elevation.

01:03After that you are having height of a pole i.e. BC.

01:06Aap jo given information hai humare paas usme humare paas height hai pole ki that is equals

01:19to 10 meters.

01:22After that, it is confusing, after that aapke paas jo shadow hai uski jo length aa rahi

01:29hai i.e. AC.

01:36Length of a shadow i.e. 10 sqrt 3 meters.

01:46Aap aap dekho ki aapne maloom kya karna hai, now you have to find alpha.

01:51Aap humare paas given information kya hai, humare paas perpendicular hai, humeshe jo

01:55straight line hoti hai, height hoti hai i.e. taken as a perpendicular, ye aapki base hai

02:00aur 90 ka angle jahaan pe banega jab bhi perpendicular hongi 2 lines uske jo opposite

02:05wali side hoti hai, humeshe high portenous hoti hai.

02:09I am repeating, aapke paas jab bhi 2 lines perpendicular hoti hai, 90 ka angle banta

02:13hai aur is angle ke opposite jo side hai, wo aapki sabse lambi side hoki, wo aapka high

02:20portenous hoka.

02:21Toh hum yaha pe sign lagayenge, why because some people have, aapka perpendicular aachayega,

02:27aapka high portenous aachayega.

02:30So like this we are going to solve the question, sign alpha perpendicular humare paas 10 meters

02:41hai aur high portenous humare paas 10 sqrt 3 hai, jab hum isko solve karenge toh 10,

02:4910 ko cancel kardega, aapke paas aachayega, sign of alpha equals to 1 over sqrt 3, dekin

02:56hume toh alpha chahiye, angle of elevation chahiye.

03:00So very simple, aap sign ko doosri taraf le jaoge, sign inverse, ok, ab hume sign inverse

03:101 over sqrt 3 ko solve karna hai, bahut simple sa kaam hai, aap shift karke, jab sign inverse

03:16laoge, 1 divided by sqrt 3 equals to 35.26, aap upto 2 decimal ne lo, upto 4 decimal lo,

03:27this is just your own choice.

03:29So this is going to be equal 35, humara jo alpha hai, wo equal ho jayega aapke paas,

03:3635.26.

03:37Aapne shift karke sign inverse laana hai, aur uske baad aap bishak pehle isko decimal

03:43form mein convert kar lein, yaar directly likh lein ki 1 divided by sqrt 3, you will

03:48get the answer.

03:49Ye humara angle of elevation hai of the sun.