in an isosceles triangle the two base angles are congruent. the third angle is the vertex angle. in any triangle the sum of the three angles will be 180°.
let v = the vertex angle
let b = each of the base angles
v + b + b = 180°
v = b + 9 (the vertex angle of an isosceles triangle is 9 degrees more than a base angle)
substitute b + 9 for v, in the equation v + b + b = 180°
(b + 9) + b + b = 180° combine like terms to simplify
1.7
Step-by-step explanation:
possible answers: -6, 6, using reverse operation method
(opposite of subtraction, use addition)
18 + 30 = 48
(opposite of division, use multiplication
48 x 3 = 144
(opposite of square, use square root and can be splitted into 2 operations)
√144
=-12 or 12
(opposite of multiplication, use division)
= -12 / 2 or 12/2
= -6 or 6
answer:
vertex angle is 66°
step-by-step explanation:
in an isosceles triangle the two base angles are congruent. the third angle is the vertex angle. in any triangle the sum of the three angles will be 180°.
let v = the vertex angle
let b = each of the base angles
v + b + b = 180°
v = b + 9 (the vertex angle of an isosceles triangle is 9 degrees more than a base angle)
substitute b + 9 for v, in the equation v + b + b = 180°
(b + 9) + b + b = 180° combine like terms to simplify
3b + 9 = 180° subtract 9 from both sides
3b = 171° divide both sides by 3
b = 57°
v = b + 9° => v = 57° + 9° = 66°
check: 57° + 57° + 66° = 180°
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