The sum of angle on a straight line is

$$
b = \sqrt{64}
$$
$$
b = 8
$$
The correct option is **(a) b=8**.

4. The sum of the three angles in a triangle is The sum of the interior angles of any triangle is always $180^\circ$. The correct option is (d) $180^\circ$.

5. Angle x and y are called ____ angles Angles x and y are on opposite sides of the transversal and between the two parallel lines. They are called alternate interior angles. The correct option is (b) alternate.

6. Sine $30^\circ$, cos $30^\circ$, tan $30^\circ$

   • $\sin 30^\circ = \boxed{\frac{1}{2}}$
   • $\cos 30^\circ = \boxed{\frac{\sqrt{3}}{2}}$
   • $\tan 30^\circ = \boxed{\frac{1}{\sqrt{3}} \text{ or } \frac{\sqrt{3}}{3}}$

7. sin $60^\circ$, cos $60^\circ$, tan $60^\circ$

   • $\sin 60^\circ = \boxed{\frac{\sqrt{3}}{2}}$
   • $\cos 60^\circ = \boxed{\frac{1}{2}}$
   • $\tan 60^\circ = \boxed{\sqrt{3}}$

8. sin $45^\circ$, cos $45^\circ$, tan $45^\circ$

   • $\sin 45^\circ = \boxed{\frac{1}{\sqrt{2}} \text{ or } \frac{\sqrt{2}}{2}}$
   • $\cos 45^\circ = \boxed{\frac{1}{\sqrt{2}} \text{ or } \frac{\sqrt{2}}{2}}$
   • $\tan 45^\circ = \boxed{1}$

9. The sum of angle at a point is The sum of angles around a central point is $360^\circ$. The answer is $\boxed{360^\circ}$.

10. Write short notes on the followings

    • a) Acute angle: An angle that measures less than $90^\circ$.
    • b) Obtuse angle: An angle that measures greater than $90^\circ$ but less than $180^\circ$.
    • c) Reflex angle: An angle that measures greater than $180^\circ$ but less than $360^\circ$.
    • d) Right angle triangle: A triangle that contains one angle exactly equal to $90^\circ$.