**Trigonometric Ratios CBSE NCERT Solutions Chapter 8 Exercise 8.2 Question 4**

**4.** State whether the following are true or false. Justify your answer.

**(i)** sin (A+B) = sin A + sin B

It is **False. **

Let A = 60 and B =30

**L.H.S =** sin (A+B) = sin(60+30) = sin(90) = 1

**R.H.S =** sin A + sin B = sin 60 + sin 30 =

**L.H.S R.H.S**

Therefore, the given statement is **False**.

**(ii)** The value of sin increases as increases.

**True. **

You can check **here** values of six trigonometric ratios **(sin, cos, tan, sec, cot and cosec)** for **0, 30, 45, 60 and 90** degrees. You can also learn from this article about how to memorize all the values in an easy way.

**(iii)** The value of cos increases as increases.

**False.**

You can check **here** values of six trigonometric ratios **(sin, cos, tan, sec, cot and cosec)** for **0, 30, 45, 60 and 90** degrees. You can also learn from this article about how to memorize all the values in an easy way.

**(iv)** sin = cos for all values of .

**False**

Example, sin 30 but cos 30

**(v) **cot A is not defined for A = 0

**True**

cot 0 **(1)**

But, sin 0 **(2)**

Putting **(2)** in **(1)**, we get

cot 0 which is **not defined**.

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