Solution:
We know that
π rad = 180°
Or, we can write:
1 rad = 180°/ π
(i) 9π/5
Using the above relation, we can write => [(180/π) × (9π/5)] o
Putting the value of π = 22/7, we get
$ =\left[ 180/22\text{ }\times \text{ }7\text{ }\times \text{ }9\text{ }\times \text{ }22/\left( 7\times 5 \right) \right] $
$ =\left( 36\text{ }\times \text{ }9 \right)\text{ }{}^\circ $
$ =324{}^\circ $
Therefore, the degree measure of 9π/5 is 324°
(ii) -5π/6
Using the above relation, we can write => [(180/π) × (-5π/6)] o
Putting the value of π = 22/7
$ =\left[ 180/22\text{ }\times \text{ }7\text{ }\times -5\text{ }\times \text{ }22/\left( 7\times 6 \right)\text{ } \right] $
$ =\left( 30\text{ }\times -5 \right)\text{ }{}^\circ $
$ =-\left( 150 \right)\text{ }{}^\circ $
Therefore, the degree measure of -5π/6 is -150°