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有人可以帮我解决这个问题吗?
Delta = 46.6 DeltaEFD面积= 1/2 * d * fsinE = 1/2 * 12 * 8 * sin105°= 46.6平方单位
您好,有人可以帮我解决这个问题吗?你如何解决:Cos2theta + 2Cos ^ 2theta = 0?
Rarrx = 2npi + -pi rarrx = 2npi + - (pi / 2)nrarrZZ rarrcos2x + cos ^ 2x = 0 rarr2cos ^ 2x-1-cos ^ 2x = 0 rarrcos ^ 2x-1 = 0 rarrcosx = + - 1当cosx = 1 rarrcosx时= cos(pi / 2)rarrx = 2npi + - (pi / 2)当cosx = -1时rarrcosx = cospi rarrx = 2npi + -pi