WAEC - Mathematics (2006 - No. 41)
In the diagram, PQR is a straight line, QRST is a parallelogram, < TPQ = 72o and < RST = 126o. What type of triangle is \(\bigtriangleup\) PQT?
An equilateral triangle
A right-angled triangle
An isosceles triangle
A scalene triangle
توضیح
< TSR = <RQT (opposite angles of a parallelogram are equal)
< PQT = 180º - 126º = 54º
<PTQ = 180º - 72º - 54º = 54º
Therefore, Angle PTQ is isosceles.