K (this has to be 20 characters long so I am typing this)
Obtuse: b^2 + c^2 > a^2
Right: b^2 + c^2 = a^2
Acute: b^2 + c^2 < a^2
A^2 + B^2 + c^2 - 2bc*cosA
As (A), is an Obtuse cos A is Negative say 2bccosA = - k then;
a^2 = b^2 + c^2 + k
a^2 > b^2 + c^2
So, your Answer would be (B)
Hope this helps!!.!
Answer:
12
Step-by-step explanation:
5^2 + b^2 = 13^2
25 + b^2 = 169
169-25= 144
take the square root of 144
answer: 12