Question

3. In a rectangle ABCD, diagonal intersects at 0. If Angle OAB = 30°, Find i) Angle ACB ii) Angle ABO
iii) Angle COD iv)Angle BOC
4. The angle between two altitudes of a parallelogram through the vertex of an obtuse angle of
the parallelogram is 60'. Find the angle of the parallelograms.
5. ABCD is a parallelogram. If AB = 4.5cm, then find the other sides of the parallelogram when
its perimeter is 21cm.

Answer 1

3.1)in rectangle diagonal intersect as 90 degree and AOBis triangle

angleAOB+angleOAB+angleOBA=180degree

90+30+OBA =180

120+OBA=180

OBA=18O-120

OBA=60

3.2)angle CBA is right angle so

angle CBO+ angle OBA =90

CBO+60=90

CBO=90-60

CBO=30

similarly in triangle cob angle o =90 and angle b=30 so

angle b+angle c+angle o=180

30+angle c+90=180

120+angle c=180

angle c=180-120

angle c=60

3.3) angle cod =90

3.4) angle boc=90

because both are angle of diagonal