Skip to main content

Back to the full dot-point answer

SingaporeMathsQuick questions

Mensuration and Trigonometry

Quick questions on Sine and cosine rules explained: O-Level E-Maths

8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is the sine rule?
Show answer
The sine rule relates each side to the sine of its opposite angle:
What is the cosine rule?
Show answer
The cosine rule generalises Pythagoras to any triangle:
What is the area of a triangle?
Show answer
When two sides and the included angle are known, the area is:
What is sign slip in the cosine rule?
Show answer
The formula subtracts 2bccos⁡A2bc\cos A; keep the minus sign, and note that an obtuse angle gives a negative cosine.
What are calculator in radians?
Show answer
Trigonometry here is in degrees, so set the calculator to degree mode.
What is q1?
Show answer
State which rule to use to find a side, given two angles and one side. [1 mark]
What is q2?
Show answer
Find the area of a triangle with sides 6 cm6\ \text{cm} and 9 cm9\ \text{cm} and an included angle of 30∘30^\circ. [2 marks]
What is q3?
Show answer
In a triangle, b=4b = 4, c=6c = 6 and the included angle A=60∘A = 60^\circ. Find aa, to 2 decimal places. [2 marks]

All MathsQ&A pages