Data Sufficiency

In the triangle, is x>90?

1) a^2+b^2<15
2) c>4

Pls explain. Thanks.

OA is C

In the triangle, is x>90?

I assume a,b,c are sides & x is one of the angle
1) a^2+b^2<15

if a^2 + b^2 =15 then hypotenuse is root(15) in that case one angle will be 90 degs but here the hypotenuse may be root 15, less than that or more that so X=90, X<90, X>90 INSUFF

2) c>4

c>4 then
we cant say, other sides are not known

combine: we have a^2+b^2<15 & c>4 so so it cannot be a right angle hence & we can say that if c=root 15 then angle oppsite to it will be 90 degs , now imagine if we increase c from root(15) while a & b are the same then the angle opposite to it will increase hence it will be greater than 90 degs.

suff C

Makes sense now....thanks a lot!