## Tuesday, October 20, 2015

### Trigonometry Basics - Quadrant Distribution and Graphical Representation of Sin Cos Tan Functions

In this video I have explained the much awaited Trigonometry Basics. First I have told about some basic formulas involving Sin Cos and Tan functions.Then I have told the values of Sin Cos and Tan in a right angled triangle. Then I have divided all angles across four quadrants of 0 to 90 degree, 90 to 180 degree, 180 to 270 degree and 270 to 360 degree. Then I have told which functions are positive in which quadrants. After that I have told that functions involving calculations keeping 180 and 360 degree as base do not change while those involving 90 and 270 degree get changed(Sin to Cos,Sec to Cosec and Tan to Cot). After that I have plotted the graphs of Sin, Cos and Tan functions.

Some questions have also been discussed by me in this video. They are as under -

Question 1. Sin 405

Question 2. Sec 315

Questions 3. Tan 240

Question 4. A man is standing at a distance of 25 meter from the bottom of the tree, and he finds that the angle of elevation of the top of the tree is 30 degree. Find the height of the tree ?

Question 5. A tower is at a distance of 40 meter from an object. From the top of the tower the angle of depression of the object is 60 degree. Find the height of the tower.

#### 1 comment:

1. sin (180 + theta) is given. This can be written as sin (270 -theta). In that case, do we change to cos or keep it as sin itself?