Answer:
For the given question the correct answer is option 'C'.
Step-by-step explanation:
For a plane triangle we have:
1) Sum of the all the interior angles is 180 degrees. Hence option 'A' is correct.
2) For a right angled triangle from Pythagoras theorem we know that [tex]H^2=a^2+b^2[/tex]
where,
H is the hypotenuse of the triangle
a,b are the sides of the right angled triangle
hence the option 'B' is also correct
3) For any triangle ABC we know that
[tex]\frac{sin(A)}{BC}=\frac{sin(B)}{AC}=\frac{sin(C)}{AB}=constant[/tex]
hence option 'D' is also correct.
Thus only incorrect answer among the given option is 'C'.