Unit Circle in Trigonometry (Why even use it?) - #3 - Trigonometry Class 11

The definition of sin, cos, tan which you have studied till now... are NOT TRUE. Well, it is for sin 45°, but what about sin 120°? The definition of sin, cos, tan we have studied till now uses a right triangle.. but for sin 120°, you cannot have a right triangle.. Then, how should we do it? Enter... Unit Circle. Unit circle is a circle of radius 1. But, how does that affect Trigonometry.. Well, all the points of a unit circle are infact sin and cos. We first study that, and then we find Value of sin, cos at 0°, 90°, 180°, 270°, 360° After that, we learn about Signs of Trigonometric Functions in all the 4 quadrants. And then, we find value of sin 120° tan 225° cos 315° sin π/3, cos 2π/3, sin 4π/3, tan 5π/3 So, keep your Pen and Notebook ready... write the Video Name on Top and start doing the questions! On Teachoo, We have explained all the questions of Class 11 Maths Chapter 3 - Trigonometry, including NCERT Solutions of all Exercise Questions as well as Examples and Miscellaneous Check it out here - https://www.teachoo.com/subjects/cbse... For Solutions to all the Maths Questions of Class 6 to 12, please check our Maths page - https://www.teachoo.com/maths/ Follow us on Instagram -   / teachoo_official   0:00 Intro 0:41 We learned 1:08 But 2:02 Enter UNIT CIRCLE 7:07 Value of sin, cos at 30, 45, 60 degree 9:11 Value of sin, cos at 0 & 90 degree 10:40 Value of sin, cos at 180, 270, 360 degree 12:51 Signs of trigonometric functions 16:30 Finding value of sin 120 degree 18:24 Finding value of tan 225 degree 20:04 Finding value of cos 315 degree 21:17 Finding value of sin, cos, tan 25:46 Finding value of cos -2pi/3