Himavad Gopal's answer to LockB's Secondary 3 A Maths Singapore question.
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Hope this helps. Let me know if you still have any clarification! Good luck
Date Posted:
3 years ago
Not true. I’m pretty sure my eyes tell me that one of the angles is obtuse.
Nevertheless, substitution back into the triangle to check whether the sum of two angles exceed 180 degrees or not is necessary for such questions.
Nevertheless, substitution back into the triangle to check whether the sum of two angles exceed 180 degrees or not is necessary for such questions.
Agree with Eric, that would be a better way to do it. Thanks
thx :)
when we use the sine rule do we always have to do sin-1(angle) or 180-sin-1(angle) when we want to find angle or does it depends on the situation whether we should do both or just the sin-1(angle)
To play safe, do both all the time if the other given angle is lower than 90.
(If the angle given is more than 90, our wanted angle cannot be obtuse already).
That said, from my experience, quite often it happens that if the other given angle is 60, then our wanted angle is usually acute. But to play safe, do both.
The smaller the other given angle, the more likely the obtuse case is possible.
(If the angle given is more than 90, our wanted angle cannot be obtuse already).
That said, from my experience, quite often it happens that if the other given angle is 60, then our wanted angle is usually acute. But to play safe, do both.
The smaller the other given angle, the more likely the obtuse case is possible.
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