Question

angle ABC is 20° how ​

Answer 1

Step-by-step explanation:

angle A + angle B + angle C= 180°

let angle A = x°

=> angle B = 3x°

angle C = 20 + x°

x + 3x + 20 + x = 180

5x + 20 = 180

5x = 160

x = 160 ÷ 5

= 32°

so the angle measure are : 32°,96° and 52°

Answer 2

Answer:

given,

AD = DC

and, angle ACD = 40

now , angle ACD = DAC ( angles opposite to equal sides are equal)

implies, angle DAC= 40

and , by angle sum property of a triangle

angle A + D + C = 180

= 40 + 40 + D = 180

= D = 180 - 80

D = 100

since , BC. is a straight line

implies , angle ADC + ADB = 180 ( linear pair )

= 100 + ADB = 180

= ADB= 180 - 100

= ADB = 80

now ,BA = BD

and , angle ADB = 80

implies , angle ADB = BAD (angles opposite to equal sides are equal )

angle BAD = 80

now, by angle sum property of a triangle

angle A + B + D = 180

= 80 + 80 + D = 180

D = 180 - 160

D = 20

how I know the sides are equal?

check the small line which cut the sides

two lines in two sides which means they are equal

one line for both means those two are equal

and the properties plz learn them