If two prisms of the same power are placed next to each other, their total power can be
Chapter 14, Problem 20(choose chapter or problem)
If two prisms of the same power are placed next to each other, their total power can be determined using the formula z = 2p cos where z is the combined power of the prisms, p is the power of the individual prisms, and is the angle between the two prisms. Verify the identity 2p cos = 2p(1 sin2 )sec .
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