2. What is the area of triangle CDE equal to? a) ½ CD∙DE∙sinCDE b) ½ CD∙DE c) CD∙DE∙sinCDE 3. If the

2. What is the area of triangle CDE equal to?
a) ½ CD∙DE∙sinCDE
b) ½ CD∙DE
c) CD∙DE∙sinCDE

3. If the sum of the squares of two sides of a triangle minus the square of the third side is less than zero, then this triangle is:
a) obtuse-angled
b) right-angled
c) acute-angled

4. Write down the cosine theorem for side SK of triangle SOK.

5. Determine the type of triangle with sides measuring 10, 6, and 7 cm.

6. In triangle MNK where angle K = 60˚ and MN = 2, find the radius of the circumscribed circle around triangle MNK.

7. If in triangle NMK, angle M = 76˚ and angle N = 64˚, then which side of the triangle is the longest?
a) MN
b) NK
c) MK

8. Determine the true statement:
a) If one of the acute angles of a right triangle is 25˚, then the other is 65˚.
b) The sum of the angles in a right triangle is 180˚.
c) The tangent of an acute angle in a right triangle is the ratio of the opposite side to the hypotenuse.
d) The square of a triangle’s side is equal to the sum of the squares of the other two sides minus twice the product of those sides times the cosine of the angle between them.

9. In triangle ABC, AB = 12 cm, BC = 6 cm, and angle B = 60˚. Find the unknown side.

10. In triangle ABC, BC = 12 cm, angle A = 60˚, and angle C = 45˚. Find side AC.