Question

The greatest angle in a triangle with sides 3 cm, 4 cm and 5 cm is ___.

• A. 180${}^{\circ }$
• B. 90${}^{\circ }$
• C. 45${}^{\circ }$
• D. 100${}^{\circ }$

Answer 1

The correct option is B 90${}^{\circ }$

Given, sides of a triangle are 3cm,4cm and 5cm.

$3^2+4^2=9+16=25=5^2$

The sides of this triangle form a Pythagorean triplet. So, this is a right-angled triangle by the converse of Pythagoras' theorem.

Thus, there exists a right angle. The sum of the other two angles will be 90${}^{\circ }$. So, the greatest angle is 90${}^{\circ }$.