Question

Question 2,4 pls tell the answer

Answer 1

Here , A is center of circle with radius " a " and B is center of circle with radius " b " we draw a line DT , As DT | | AB .

And

AS = AC = a and BT = BC = b

We know " A tangent to a circle is perpendicular to the radius at the point of tangency . "

So,

AST = BTS = 90 , So

BT | | AS ( As consecutive interior angles are supplementary if we take ST as transversal line )

Then ,

ABTD is a parallelogram , So

AD = BT = b and AB = DT = a + b

And

SD = AS - AD = a - b

Now we apply Pythagoras theorem in triangle DST and get

DT2 = SD2 + ST2

ST2 = DT2 - SD2

ST2 = ( a + b ) 2 - ( a - b )2

ST2 = ( a 2 + b 2 + 2 a b ) - ( a 2 + b 2 - 2 a b )

ST2 = a 2 + b 2 + 2 a b - a 2 - b 2 + 2 a b

ST2 = 4 a b

Answer 2

2)  Twelve men can complete a work in 8 days. So a job requires 12∙8 or 96 man days.Three days after they started the work. That was 12∙3 or 36 of the required number of 96 man days.So 96-36 or 60 more man days were needed. 3 more men joined them.So that made 15 men to complete the remaining 60 man days.So 60 man days divided by 15 men gives 4 days. So the answer is b.

Hope this helps....