Sine rule and cosine ruleIB MYP Maths Extended: Flashcards

What these 13 flashcards ask

State the sine rule.
State the cosine rule for a side.
State the cosine rule for an angle.
When do you use the sine rule?
When do you use the cosine rule?
What is an included angle?
What does a negative cosine mean for an angle in a triangle?
Two angles and one side are known. What is the first step?
Which side is opposite the largest angle?
Sides 6 and 10 with included angle 120^\circ: third side?
Which side goes on the left of a^2=b^2+c^2-2bc\cos A?
Why is the cosine rule safer for finding an angle?
What should you do with full calculator values in a multi-step problem?

Exam questions on Sine rule and cosine rule

In triangle $ABC$ , $B\hat AC=40^\circ$ , $A\hat BC=65^\circ$ and $BC=12$ cm.
Explain why the cosine rule is not the best first step to find $AC$ .2 marks
In triangle $PQR$ , $PQ=6$ cm, $PR=10$ cm and $Q\hat PR=120^\circ$ .
Find the exact value of $\cos P\hat QR$ .2 marks
Two points $A$ and $B$ are on a straight shoreline, 800 m apart. A boat is at the point $C$ out at sea, with $C\hat AB=52^\circ$ and $C\hat BA=71^\circ$ .
Find the distance $AC$ from the boat to the point $A$ .3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).