Question

Q.57.
If 7a2+7b2+7c2-7ab-7bc-7ca=0, then find the value
Q.58
a + b
of -
с+а
(A) 2 (B)1 (C)-1 (D)
Two circles of same radius 5 cm, intersect each
other at P and Q. If distance between the ce tres is
6 cm. Find the length of PQ.
(A) 10 cm. (B) 8 cm. (C) 6 cm. (D) 12 cm.
ово​

Answer 1

Answer:

Vikas ke sath fiji hua kya hua hai

Answer 2

Answer:

(B) 8 cm

Step-by-step explanation:

Part II

As per the question,

Let the two circle with center O and O' are drawn below:

OP ( radius) = O'P ( radius) = 5 cm

OO' = 6 cm

Now,

Let PR = x

Using Pythagoras theorem in Δ OPR

$OR =\sqrt{5^{2}-x^{2}}$                            ..........(i)

Similarly in  Δ O'PR

$O'R =\sqrt{5^{2}-x^{2}}$                           ...........(ii)

Add equation (i) and (ii), we get

$OR+O'R =\sqrt{5^{2}-x^{2}}+\sqrt{5^{2}-x^{2}}$

Since OR + O'R = OO' = 6 cm

$6=2 \times \sqrt{5^{2}-x^{2}}$

$3=\sqrt{5^{2}-x^{2}}$

On squaring both sides, we get

9 = 25 - x²

x² = 16

x = 4

∴ PR = 4 cm

Also PR = QR

Therefore,

Length PQ = 2 × PR = 8 cm

Hence, the length of PQ = 8 cm.