Answer:
Height of the object is 68.6 cm.
Step-by-step explanation:
The height of the object can be determined by:
= 
From the given question;
object distance from pinhole = 3.6 m = 360 cm
image distance from pinhole = 4.2 cm
height of image = 0.8 cm
So that;
= 
⇒ object height = 
= 
= 68.571
object height = 68.6 cm
Thus, the height of the object is 68.6 cm.
Let the original number be ‘x’
Then half of that number= 1/2x or simply x/2
Similarly one fifth of that number = x/5
According to the question
x+x/2+x/5=51
Taking LCM
10x/10+2x/10+5x/10=51
Multiplying 10 throughout
10x+2x+5x=510
17x=510
x=510/17
Therefore x=30
Answer:
ang hirap wag nlang hahahahahahahaha

It is true only whenever x tends to 0(zero)
it is not importent that x be in radian or in degree.