Edexcel IGCSE Maths 復習筆記 4.10.2 Sine & Cosine Rules, Area of Triangle - Harder
Edexcel IGCSE Maths 復習筆記 4.10.2 Sine & Cosine Rules, Area of Triangle - Harder
Choosing which rule or formula to use
- It is important to be able to decide which Rule or Formula to use to answer a question
- This table summarises the possibilities:
Using the cosine rules to find angles
Exam Tip
In more involved exam questions, you may have to use both the Cosine Rule and the Sine Rule over several steps to find the final answer.If your calculator gives you a ‘Maths ERROR’ message when trying to find an angle using the Cosine Rule, you probably subtracted things the wrong way around when you rearranged the formula.The Sine Rule can also be written ‘flipped over’:
This is more useful when we are using the rule to find anglesWhen finding angles with the Sine Rule, use the info in the question to decide whether you have the acute angle case (ie the calculator value) or the obtuse angle case (ie, minus the calculator value).The Cosine Rule will never give you an ambiguous answer for an angle – as long as you put the right things into the calculator, the answer that comes out will be the correct angle
Worked Example
In the following triangle:
a) Find the size of angle ABC.
b) Given that angle ACB is obtuse, use the Sine Rule and your answer from (a) to find the size of angle ABC.
Give your answers accurate to 1 d.p.
Worked Example
轉載自savemyexam
以上就是關于【Edexcel IGCSE Maths 復習筆記 4.10.2 Sine & Cosine Rules, Area of Triangle - Harder】的解答，如需了解學校/賽事/課程動態，可至翰林教育官網獲取更多信息。
往期文章閱讀推薦：
MIT官方發布【2026年夏季推薦閱讀書單】！橫跨科學/人文/經濟...
深耕九載！30+國際競賽/課程講義，碩博100%團隊操刀，助力爬藤沖G5！
翰林AMC8視頻課重磅上線！
國際競賽真題資源免費領取
