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secondary 4 | A Maths
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littleredridinghood
Littleredridinghood

secondary 4 chevron_right A Maths chevron_right Singapore

urgent help thanks

Date Posted: 3 years ago
Views: 332

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William Ng
William Ng's answer
58 answers (Tutor Details)
the key thing is using concept of toa cah soh
littleredridinghood
Littleredridinghood
2 years ago
thankyou
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tan xing yee
Tan Xing Yee's answer
4 answers (Tutor Details)
using pythagoras theorem to find cos2A, 2A as the angle. not sure if it’s correct, hope that it’s helpful!
Eric Nicholas K
Eric Nicholas K
3 years ago
But then if 45 < A < 90, then it follows that 90 < A < 180 so 2A is a second quadrant angle, so cos 2A will have a negative value (after Pythagorean Theorem is applied)