Sine Or Cosine Rule?

The video explains how to use the sine and cosine rules to find missing sides or angles in triangles that are not right-angled. It emphasizes the importance of labeling sides and angles correctly, with sides labeled as a, b, c and angles as A, B, C, where each side is opposite its corresponding angle. The sine rule requires one complete pair of a side and its angle, and half of another pair. The cosine rule is used when all three sides are known, or when two sides and the included angle are given. The video provides examples and encourages viewers to practice using these rules.

What is the primary condition for using the sine rule in a triangle?

• The triangle must be equilateral.

• All three sides must be known.

• There must be one complete pair of a side and its angle.

• The triangle must be right-angled.

In the sine rule, how should the sides and angles be labeled?

• Sides with numbers and angles with letters.

• Sides and angles with the same letters.

• Sides with capital letters and angles with lowercase letters.

• Sides with lowercase letters and angles with capital letters.

Why can't the sine rule be used if there are no complete pairs?

• Because it requires a right angle.

• Because it needs a complete pair to establish a ratio.

• Because it only works with equilateral triangles.

• Because it requires all angles to be known.

When is the cosine rule applicable?

• When there is one complete pair of a side and its angle.

• Only in right-angled triangles.

• When the triangle is isosceles.

• When all three sides are known or side-angle-side is given.

What does 'cosy cosine hugs the angle' refer to?

• The need for a right angle in the cosine rule.

• The cosine rule's requirement of side-angle-side.

• The sine rule's requirement of a complete pair.

• The labeling of sides and angles in the sine rule.