Question

Two concentric circles are of radii 4
cm and 5 cm. Find the length of the
chord of the larger circle which
touches the smaller circle.
estione​

Answer 1

Answer:

I thik answer is 9 of this question

Answer 2

Explanation of the diagram [ refer attached picture for diagram] :-

➡ Two concentric circles are of radii 4

cm and 5 cm.

➡ OP( 4 cm) is radius of smaller circle with center O.

➡ OQ( 5 cm) is radius of larger circle with center O.

➡ OP bisect QR into two equal parts. Therefore, QP=PR.

➡ QP + PR = QR [ QR is chord of larger circle and tangent for smaller circle ]

Now , ∆OPQ is a right angled triangle.

We will find QP by using Pythagoras theorem.

Let QP be x cm.

According to the question :-

$\tt \longrightarrow {x}^{2} = {5}^{2} - {4}^{2}$

$\tt \longrightarrow {x}^{2} = 2 {5} - 16$

$\tt \longrightarrow {x}^{2} =9$

$\tt \longrightarrow {x} = \sqrt{9}$

$\tt \longrightarrow {x} = 3$

QP = PR = x = 3 cm

➡ QP + PR= QR

➡ 3 cm + 3 cm = QR

➡ 6 cm = QR

Length of the chord of the larger circle = 6 cm