Question : If the external angle of a regular polygon is 18°, then the number of diagonals in this polygon is:
Option 1: 180
Option 2: 150
Option 3: 170
Option 4: 140
Latest: SSC CGL preparation tips to crack the exam
Don't Miss: SSC CGL complete guide
New: Unlock 10% OFF on PTE Academic. Use Code: 'C360SPL10'
Correct Answer: 170
Solution : Given, Each exterior angle of a polygon is 18°. We know that the sum of the exterior angles of a polygon is 360°. Number of sides of polygon = $\frac{360°}{\text{each exterior angle}}$ ⇒ Number of sides of regular polygon, $n$ = $\frac{360°}{18°} = 20$ $\therefore$ Number of diagonals = $\frac{n(n-3)}{2}=\frac{20(20-3)}{2}=170$ Hence, the correct answer is 170.
Candidates can download this ebook to know all about SSC CGL.
Answer Key | Eligibility | Application | Selection Process | Preparation Tips | Result | Admit Card
Question : If the interior of a regular polygon is 170$^\circ$, then the number of sides of the polygon is:
Question : The interior angle of a regular polygon exceeds its exterior angle by 90°. The number of sides of the polygon is:
Question : If one of the interior angles of a regular polygon is $\frac{15}{16}$ times of one of the interior angles of a regular decagon, then find the number of diagonals of the polygon.
Question : In $\triangle$XYZ, P is the incentre of the $\triangle$XYZ. If $\angle$XYZ = 50°, then what is the value of $\angle$XPZ?
Question : Find the number of diagonals of a regular polygon, whose sum of interior angles is 2700°.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile