Question

Find x give brief reason

Answer 1

Q1 . By pytagorean therom ,

CA ^ 2 + AB ^2 = BC^2

2^2 +4^2 = BC^2

4 + 16 = BC ^2

20 = BC^2

BC =
`√(20)`

BC = 4.4

1/2 BC = x = 2.2 ( Midpoint)

Q2 .

OQP = 90

(5+X)^2 = X^2 + 7^2

25 + 10X + X^2 = X^2 + 49

25 + 10X = 49

10X = 49 - 25 = 24

X = 2.4

Answer 2

see explanation

Explanation:

(a)

the angle in a semicircle is a right angle , then Δ ABC is right with ∠ BAC = 90°

the radius of the circle OB = x , then BC = 2x

using Pythagoras' identity in the right angle

BC² = AB² + AC²

(2x)² = 4² + 2²

4x² = 16 + 4 = 20 ( divide both sides by 4 )

x² = 5 ( take square root of both sides )

x =
`√(5)`

-----------------------------------------------------------------

the angle between a tangent and the radius of the circle at the point of contact is 90° , that is

∠ OQP = 90° and Δ OPQ is right

note that OP = 5 + radius = 5 + x

using Pythagoras' identity in the right triangle

OP² = OQ² + PQ²

(5 + x)² = x² + 7² ← expand left side using FOIL

25 + 10x + x² = x² + 49 ( subtract x² from both sides )

25 + 10x = 49 ( subtract 25 from both sides )

10x = 24 ( divide both sides by 10 )

x = 2.4