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If A+B+C=^(^=180) prove that sinA + sinB - sinC = 4sinA/2 sinB/2 cosC/2

find the value of : sin18'

Which are true and which are false? 1: the increase in carbon dioxide since the year 1860 is similar to the past increases. 2: atmospheric composition has remained constant throughout earths history. 3: climate has changed naturally over earths history 4:...