Special Properties, SMB-016

Two identical quadrilaterals fit together to make this regular pentagon.

What is the value of `x`? (2 marks)

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`108^@`

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`text(Consider regular pentagon:)`

`text{Sum of internal angles (formula)}`

`= (n-2) xx 180`

`= 3 xx 180`

`= 540^@`

`:. x`	`= 540/5`
	`= 108^@`

TIP: Two quadrilaterals joining does not make the internal angle sum = 2 × 360°!