Final answer:
The line type described as having ten syllables arranged in five sets of alternating unstressed and stressed syllables is known as Iambic Pentameter. This meter is prominently used in Shakespearean sonnets, such as 'Sonnet 18', and is characterized by its da-dum heartbeat-like rhythm.
Step-by-step explanation:
The type of line that is roughly ten syllables arranged in five sets of alternating unstressed and stressed syllables is known as Iambic Pentameter. This style of poetic meter is most notably used in the works of William Shakespeare, such as his Sonnet 18 which begins with the line 'Shall I compare thee to a summer's day?'. Each line of a poem written in iambic pentameter consists of five iambs, which are two-syllable units with the first syllable being unstressed, followed by a stressed syllable, resembling the pattern da-dum, much like the sound of a heartbeat.
In contrast to other forms like the Haiku, which is a three-line form with a syllable pattern of 5-7-5 and usually deals with nature, or the Tanka, which has a syllable count of 5-7-5-7-7, Iambic Pentameter is more fluid and allows for a rhythmic quality that resembles natural speech. While sonnets are traditionally composed of fourteen lines in iambic pentameter, it is the iambic pentameter itself that defines the line structure in question.
It is important to note that while a poetic line in iambic pentameter usually contains exactly ten syllables, at times poets such as Shakespeare have added an eleventh syllable for stylistic effect, as seen in the famous line from Hamlet, 'To be, or not to be: that is the question'. This occasional variation does not change the fundamental structure of the iambic pentameter line.