In isosceles PQR, P is the vertex angle. If mQ = 8x - 3 and mR = 2x + 15, find the measure of P.
3
21
42
138
please help me i reallly dont know which one it is. lol i have been working on this problem for lke 20 minutess
please and thanks<3
2007-11-13 02:45:56 · 2 answers · asked by Dianalynn 1 in Science & Mathematics ➔ Mathematics
Sorry, I misread the problem earlier.
In an isosceles triangle, the base angles
are congruent. So
8x-3 = 2x+15
6x = 18
x = 3
8*3-3 = 21
So the base angles are each 21 degrees
Then 21+21+angle P = 180
So angle P = 138 degrees.
2007-11-13 02:54:27 · answer #1 · answered by steiner1745 7 · 0⤊ 1⤋
In an isosceles triangle, base angles are equal and
Base angles + Vertex Angle = 180
In isoceles PQR, mQ and mR are base angles and mP is the vertex angle
Since base angles are equal
mQ = mR
8x - 3 = 2x + 15
8x - 2x = 15 + 3
6x = 18
x = 18/6 = 3
mQ = 8x - 3 = 8*3 - 3 = 24 - 3 = 21
mR = 2x + 15 = 2*3 + 15 = 6 + 15 = 21
mQ + mR + mP = 180
21 + 21 + mP = 180
mP = 180 - 21 -21
mP = 138
Hope that helps
2007-11-13 10:56:11 · answer #2 · answered by gmat g 3 · 0⤊ 1⤋