[5] Find the locus of a point fixed in a straight line of constant length which moves with its extremities on two fixed straight lines, making an angle with each other. To what family of curves does the locus belong ? 2019.03.27記 [5] 角度…

[1] （物理學）A cubic meter of air is heated under the normal atomospheric pressure until its volume is doubled. How much of the heat supplied to it is converted into external work.[2] （物理學）Explain how the velocity of sound in air var…