JAMB - Mathematics (1979 - No. 18)
A ladder resting on a vertical wall makes an angles whose tangent is 2.4 with the ground. If the distance between the foot of the ladder and the wall is 50cm, What is the length of the ladder?
1m
1.1m
1.2m
0.9m
1.3m
คำอธิบาย
If tan\(\theta\) = 2, 4
\(\theta\) = tan-1(2.4)
= 67o 25
By sin formula \(\frac{x}{sin 90^o}\) = \(\frac{50}{sin 22^o 37}\)
= \(\frac{50}{sin(9o - \theta)}\)
sin90o = 1
x = 50 cosec 22o 37
= 50 x 2.604x
= 130cm
but 100cm = 1m
130cm = 1.3m
\(\theta\) = tan-1(2.4)
= 67o 25
By sin formula \(\frac{x}{sin 90^o}\) = \(\frac{50}{sin 22^o 37}\)
= \(\frac{50}{sin(9o - \theta)}\)
sin90o = 1
x = 50 cosec 22o 37
= 50 x 2.604x
= 130cm
but 100cm = 1m
130cm = 1.3m