1) a^2 + b^2 < 15,

pick two values, a & b e.g. 2,3

<c is 90, when c = 5, however, c should always be <5 , so <c is never > 90. You can try taking other possible values and shud get the same answer.

2) Not sufficient

So, I will go with A.

mbaquest wrote:1) a^2 + b^2 < 15,

pick two values, a & b e.g. 2,3

<c is 90, when c = 5, however, c should always be <5 , so <c is never > 90. You can try taking other possible values and shud get the same answer.

2) Not sufficient

So, I will go with A.

OA is C. Can someone plz. explain

I guess I was wrong the last time. However C seems to be right.

Here is my explanation,

In a triangle with sides A, B & C and corresponding angles a,b,c

C^2 = A^2 + B^2 - 2AB cos c

1) A^2 + B^2 < 15, we can have multiple values of c, depending on the value of C

Not sufficient

2) C > 4,

No information about A & B so not sufficient.

3) Taking both together,

As C > 4 the term -2AB cos c must be +ve, so cos c should be -ve.
cos c is negetive when c > 90.

Sufficient.

Is there any other way to answer this question, without using trigonometry?

acc to pythagorous theoram,

In rt angle triangle

a^2 + b^2= c^2


stmt a A^2 + B^2 < 15----

no value for c---insufficient

stmt b-c>4

no values for a & b--insufficient

combining both,a^2 + b^2<c2....So it must be greater than 90..Hope it helps..IMO C

hi all,

answer is C. when both conditions are conbined, we can difine x>90:

c>4, so c^2>16 and a^2+b^2<15, that is 15<16 so we get x<90

hint: if a^2+b^2<c^2, x>90, and if a^2+b^2>c^2, x>90.

stubbornp wrote:acc to pythagorous theoram,

In rt angle triangle

a^2 + b^2= c^2


stmt a A^2 + B^2 < 15----

no value for c---insufficient

stmt b-c>4

no values for a & b--insufficient

combining both,a^2 + b^2<c2....So it must be greater than 90..Hope it helps..IMO C

Hello
could you explain using values please

Note: A right triangle will ALWAYS follow= A^2 + B^2= C^2

1) NS--> We have A and B but no C... Could be greater than 90 or less. We dont know.. Move on

2) We get C as a number greater than 4.. We have no idea about A or B so we move on.. NS

1) and 2)--> A^2 +B^2<15= Assume- 2^2 + 3^2= 4+9= 13... But BECAUSE C^2 HAS TO BE GREATER THAN 16, we think Pythag's theorem and figure out that it MUST be greater than 90 degrees and thus SUFFICIENT!!!!

ANSWER: C

Let me know if this helps!

we need to find if x>90
or in other words c^2 > a^2 + b^2

1. a^2 + b^2 <15
no info about c ... hence Insuff

2. c>4 => c^2 > 16
no info abt a&b ... hence Insuff

combining both we know
c^2 > a^2 + b^2
hence Suff

So ans is C

ANS : C
Please refer to the attached figure...