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junior college 2 | H2 Maths
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Zachary
Zachary

junior college 2 chevron_right H2 Maths chevron_right Singapore

How do I represent A in alpha?

Date Posted: 3 years ago
Views: 570
J
J
3 years ago
Left triangle :

Using sine rule,

(a/2) / sin(120°- α) = B / sin60°

a / 2sin(120° - α) = 2B / √3

2B = a√3 / 2sin(120° - α)

B = a√3 / 4sin(120° - α)

B = a√3 / 4(sin120° cos α - cos120° sin α)

B = a√3 / 4(√3/2 cos α - (-½ sin α) )

B = a√3 / 2(√3 cos α + sin α)


Area of A → formula ½ab sin c

= ½(a/2)(B) sin α

= (a/4) (a√3 / 2(√3 cos α + sin α) ) sin α

= a²√3 sin α / 8(√3 cos α + sin α)