The Credible Cosine is a dramatic poetic form, originating in The Mighty Flags. The rules of the form are applied by poets to produce individual poems which can be recited. The poem is divided into three distinct parts: a quatrain, a line and another line. A form of parallelism is common throughout the poem, in that certain lines sometimes have reversed word orders. Each line has nine syllables. Every line of the poem has a terminal caesura.