Question

if ABC is an obtuse angled triangle. angle b is an obtuse angle and AD is perpendicular to BC. then AC square is
​

Answer 1

Step-by-step explanation:

In the right angle triangle ABD, we have 

         AD² = AB² - BD²

In the right angle triangle  ACD we have 

        AD² = AC² - CD²

So    AC² - CD²  = AB² - BD²

        =>  AC² = AB² + CD²  -  BD²

        =>         = AB² + (CD + BD)* (CD - BD )

                     = AB² + BC * [(BC - BD) - BD]

                     = AB² + BC * [ BC - 2 BD ]

                       = AB² +BC² - 2 BC * BD

Answer 2

Answer:

as it is obtused at b so u have to draw a perpendicular(ad) at bc produced to d then

ac^2 =ad^2+dc^2