Suppose a triangle has sides a, b, and c, and let theta be the angle opposite he side length of a. If costheta0 , what must be true? a- a^2+b^2=c^2 b-b^2+c^2c^2 d-b^2+c^2a^2

Question

Suppose a triangle has sides a, b, and c, and let theta be the angle opposite he side length of a. If costheta>0 , what must be true?
a- a^2+b^2=c^2
b-b^2+c^2<a^2
c-a^2+b^2>c^2
d-b^2+c^2>a^2

welshfella · Answer

If cos theta > 0 then it must be an angle < or equal to 90 degrees

anonymous · Answer

so its either a or b?

welshfella · Answer

It cannot be b because that would make theta > 90 degrees

welshfella · Answer

B would be an obtuse angled triangle

mathmath333 · Answer

u can use law of cosine here

welshfella · Answer

Note that a is a right angled triangle because of Pythagoras theorem so a would be an angle with a cosine > 0  but it does not have to be a right angled triangle for this to be the case

welshfella · Answer

Yes @matmat333