measure of angle B= 110ft² = 20ft² + 120ft² - 2(110)(20)cosB

Then you can find angle a with...

180 - (angleB + angleC)

Gster's way is much simpler lol.

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"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."

George Bernard Shaw - Man and Superman