Hello! This is a question I couldn't solve. If A is an obtuse angle in a triangle and sin A = 5/13, calculate the exact value of sin 2A. I would appreciate your help, Amine
Follow Math Help Forum on Facebook and Google+
Originally Posted by Aminekhadir Hello! This is a question I couldn't solve. If A is an obtuse angle in a triangle and sin A = 5/13, calculate the exact value of sin 2A. I would appreciate your help, Amine HI A would be in the second quadrant since sin A is positive and its obtuse . Then by phythagoras , the other side would be 12 so cos A = - 12/13 (negative because cos is negative in 2nd qua) sin 2A = 2 sin A cos A=2(5/13)(-12/13)
View Tag Cloud