In the given right-angled triangle with base AT = 12 and height BT = 6, applying the Pythagorean theorem yields the hypotenuse
units. In another scenario involving tangent circles and angles, the measure of angle ∠TDC is found to be 74° when x = 9°.
In a right-angled triangle, the Pythagorean theorem can be used to find the length of the hypotenuse (the side opposite the right angle). The Pythagorean theorem is given by:

where:
- c is the length of the hypotenuse,
- a and b are the lengths of the other two sides.
In your case, the base of the triangle is AT = 12 and the height is BT = 6. Let's denote the hypotenuse as AB = c .
![\[ c^2 = 12^2 + 6^2 \]](https://img.qammunity.org/2024/formulas/mathematics/college/bu4v4i7q2zvsfnar446qavusmdjq7h3dc7.png)
![\[ c^2 = 144 + 36 \]](https://img.qammunity.org/2024/formulas/mathematics/college/rfc2x00q3d17isus4nv7bwbd2cuu9rhg98.png)
![\[ c^2 = 180 \]](https://img.qammunity.org/2024/formulas/mathematics/college/12jtdt259l93ij34n2et8zxkla4vjmblos.png)
Now, take the square root of both sides to find \( c \):
![\[ c = √(180) \]](https://img.qammunity.org/2024/formulas/mathematics/college/pd8bqdi2f8ztw45xvslif87zt07z67otbx.png)
![\[ c = √(36 * 5) \]](https://img.qammunity.org/2024/formulas/mathematics/college/xl4nzq95cejo0so7ru5vld8a4vnlzgqn4o.png)
![\[ c = 6 √(5) \]](https://img.qammunity.org/2024/formulas/mathematics/college/tc7chgq4p501j439xt31ad67tqiuqrmpf6.png)
So, the length of the hypotenuse \( AB \) is
units.
17. Since AB and CD are tangent to circle O at points B and C, we know that ∠ABO and ∠CDO are right angles.
We can also see that ∠ABT and ∠CDT are inscribed angles that subtend the same arc, BD. Therefore, we know that ∠ABT = ∠CDT.
We can use the same logic to find that ∠TBC = ∠ADC.
Now, let's consider triangle ACD. We know that
∠ACD + ∠ADC + ∠CAD = 180° (because the sum of the angles in a triangle is 180°). We can also substitute ∠TBC and ∠ABT for ∠ACD and ∠ADC, respectively. So, we have:
∠TBC + ∠ABT + ∠CAD = 180°
Substitute in the values we know:
(4x + 4)° + (8x + 2)° + 66° = 180°
Combine like terms:
12x + 72° = 180°
Subtract 72° from both sides:
12x = 108°
Divide both sides by 12:
x = 9°
Substitute 9° for x in the expression for ∠TDC:
m∠TDC = (8 * 9°) + 2°
Calculate:
m∠TDC = 72° + 2°
Therefore, m∠TDC = 74°.