Exterior Angle Property of a Triangle

Q. Find the area of an equilateral triangle whose perimeter is 12 cm.

1. 3.46 sq. cm
2. 6.92 sq. cm
3. 8.65 sq. cm
4. 5.19 sq. cm

Q.

In $△DEF$, the exterior angle at D measures ${150}^{\circ }$ and $\angle E$ measures ${80}^{\circ }$. Which of the following options show the correct relation?

1. DF $>$ DE
2. DE $<$ EF
3. DF $<$ DE
4. DF $<$ EF

Q. In triangle ABC, AB = AC and BD, CE are its two medians. Show that BD = CE.

Q. The sum of all three interior angles in a right angled triangle is equal to ___.

1. 360${}^{\circ }$
2. 90${}^{\circ }$
3. 240${}^{\circ }$
4. 180${}^{\circ }$

Q. ABC is a triangle, right angled at B. If BCDE is a square on the side BC and ACFG is a square on AC, then AD = .

1. BF
2. BC
3. BE

Q. The sum of all three interior angles in an acute-angled triangle is equal to .

1. 45${}^{\circ }$
2. 90${}^{\circ }$
3. 180${}^{\circ }$

Q. ABC is a triangle, right angled at B. If BCDE is a square on the side BC and ACFG is a square on AC, then AD = .

1. BE
2. BC
3. BF