Feb Form 3 Week 1 (Chapter 3: Circle's "part 1:Common Sense" Questions)

we start our class with Chapter 1 and 2's revision
and for the last 20 mins we do,

part 1:Common Sense
why I name it as Common sense?
It's form 2 related stuff, "CHORD" related.

Step to solve
l. Draw from Center point to CHORD (refer second picture, the red colour line O to D)

2. You will form a "Right-Angled Triangle"

3. Apply "Pythagoras' Theoram"

4. solve it for the ANSWER.