Question

If 2a = 80 and b = c, what is the measure of b

A.) 40
B.) 50
C.) 80
D.) 100​

Answer 1

From what I can tell from the image, b is equivalent to B.) 50°

Explanation:

So to start off 2a=80° there is 2 a's. so you subtract 80° from 180° to get 100°.

now b=c and their is 100° left over. So 100°/2 is 50° because if b=50° and c=50° both angles equal 100°.

Answer 2

Answer : The correct option is, (B) 50

Explanation:

As we are given :

2a = 80

b = c

As we know that:

The sum of interior angles of a triangle is equal to
`180^o`.

That means,

`\angle A+\angle B+\angle C=180^o`

`80^o+\angle B+\angle C=180^o`

and,
`\angle B=\angle C`

So,

`80^o+2\angle B=180^o`

`2\angle B=180^o-80^o`

`2\angle B=100^o`

`\angle B=(100^o)/(2)`

`\angle B=50^o`

Thus, the value of 'b' is
`50`