 Hello friends. So in this session, we are going to discuss the values of different trigonometric ratio for some specific angles So we are going to start with angle equal to zero degree That means in this case if you see the angle which angle I'm talking about. I'm talking about BAC So angle BAC here is 52.88 degrees. So at different different values of Angle, what are the values of trigonometric ratios? We are interested in interesting We are interested to know now the thing is we are not going to discuss all Angles we are going to discuss only some specific angles because There will be infinitely many possibilities of angles and for that there will be six ratios for all angles will have So for any given angle will have six ratios possible But we are going to restrict only to only those specific angles for example some standard values like 0 degree Then 45 degrees 30 degrees 60 degrees and 90 degrees So in this session, we are going to start with the angle 0 and 90 and let us let us see What are the values of different T ratios when angle alpha is 0 or theta is 0? So now what I'm going to do is I'm going to move this point B Towards the x-axis and try to make the angle 0. So as you can see I'm moving this Point B towards the x-axis the perpendicular length is Getting shortened and shortened while the base B is increasing and eventually as B coin sides with point C The length of the base is now equal to the radius So if you can see base has become equal to the length of the radius the perpendicular has just vanished That means there is no perpendicular any further or the length of perpendicular is 0 So you can see P upon H here is 0 right? Similarly B upon H base is 1 radius H is 1 so hence it is 0 so cos of 0 is 1 sign of 0 is 0 Tan of 0 is 0 because again perpendicular length is 0 Co-secant is in undefined actually so undefined means why because the perpendicular length is 0 and Secant is secant 0 is 1 because both H and B are 1 and caught again is undefined though It has been shown as infinity over here now if you see As now I will move this point B back towards y-axis now alpha value or theta value in this case is changing and Now the base is getting reduced and the perpendicular is constantly getting increased and now as I merge this point B on the y-axis now if you see P is now equal to H which is equal to 1 right H is equal to 1 and P has now become Same as hypotenuse so there is no triangle any further but the length P the the perpendicular length P is 1 and Hypotenuse is 1 anyways, which was our defined lengths of the two triangles and now the base has disappeared It is 0 right and accordingly if you see sin theta is P upon H which has become 1 now So 90 sin 90 is 1 Cos 90 is 0 and 90 is again very huge number Because you're dividing your B is 0 so you're dividing a number by 0 Which is almost infinity, but we say it is not defined because it's dividing by 0 is not defined Co-secant is 1 upon sin so you can get you can see 1 here Secant is again H by B or hypotenuse by base so base adjacent is 0 here So B value is 0. So hence again it is undefined it is showing some very big number over here And cot theta is B by P again 0 why because B is 0 and P is 1 right so hence we saw that sine of 90 so you can see sine of 90 is 1 and Sine of 0 is 0 while cos of 90 is 0 cos of 0 is 1 so you have to basically remember all these values if you know sine and cos you can find out all other values Because we know how to convert all the t ratios in terms of the other ratios We have seen this in the previous such sessions now. We'll take up the same thing for different angles some other standard angles like 30 degrees 45 degrees and 60 degrees