Answer:
<em> SSS</em><em> can be used to prove that the given triangles are congruent.</em>
Step-by-step explanation:
In the given two triangles ΔADC and ΔABC,
- AD = AB = 7 units,
- CD = BC = 8 units,
- AC is common to both triangles,
Hence, ΔADC ≅ ΔABC by Side-Side-Side (SSS) congruence.
SSS congruence-
If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent.
Answer:
a = 15
Step-by-step explanation:
Substitute b = 12 , a = 9 into the equation
12 = 
12 =
← square both sides
144 = a² - 81 ( add 81 to both sides )
225 = a² ( take square root of both sides )
±
= a , then
a = ± 15
a > 0 , so a = 15
The answer is step 2, he should have subtracted the 9 or added the six when he was moving x's...