Question

which is the true of the following ?
(A)Any vector $\overrightarrow{r}$ in space can be written as $(\overrightarrow{r}.\hat{i})\hat{i}+(\overrightarrow{r}.\hat{j})\hat{j}+(\overrightarrow{r}.\hat{k})\hat{k}$
(B)If $\overrightarrow{a}$ is perpendicular to \overrightarrow{b}$$|\overrightarrow{a}+\overrightarrow{b}|^2=|\overrightarrow{a}|^2+|\overrightarrow{b}|^2

(C)If $|\overrightarrow{a}|=2,|\overrightarrow{b}|=1$ and $\overrightarrow{a}.\overrightarrow{b}=1$ ,the value of $(3\overrightarrow{a}-5\overrightarrow{b}).(2\overrightarrow{a}+7\overrightarrow{b})$ ia 1
(D) $\overrightarrow{a}=5\hat{i}-\hat{j}-3\hat{k}$ and $\overrightarrow{b}=\hat{i}+3\hat{j}-5\hat{k}$, is the angle between $\overrightarrow{a}+\overrightarrow{b}$ and $\overrightarrow{a}-\overrightarrow{b}$ is $60\degree$
Choose thecorrect a nswer from the options given below:

• A. (A) and (B) Only
• B. (B) Only
• C. (C) Only
• D. (D) Only

Answer 1

Answer: (A)

(A) and (B) Only

Answer 2

The correct option is (A):(A) and (B) Only