Let a = cos 10$°$, b = cos 50$°$ and c = cos 70$°$
Q. The value of ($a^2+b^2+c^2$) is equal to 

• 2
• 3/2
• 4/3
• 1

Q. The value of (b+c) is equal to

1. a
2. a/2
3. 2a
4. 2a/3

Q. The value of 4($a^2-bc$) is equal to

1. 8/3
2. 5/2
3. 2
4. 3