We know that the sum of all angles of a triangle = 180°
∴ ∠A + ∠B + ∠C = 180°
⇒ ∠C + 45° + 105° = 180°
∴ ∠C = 180° - 150° = 30°
Step 1: Draw BC = 7 cm.
Step 2: At point B, draw a ray at ∠B = 45°.
Step 3: At C, draw a ray making an angle of 30° with BC intersecting the previous ray at A.
Step 4: Draw any ray BX making an acute angle with BC on the side opposite to the vertex A.
Step 5: Locate 4 points B1, B2, B3 and B4 on BX so that BB1 = B1 B2 = B2 B3 = B3 B4.
Step 6: Join B4C and draw a line through B3 || B4C to intersect BC at C′.
Step 7: Draw a line through C′ parallel to the line CA to intersect BA at A.
Thus, ΔA’BC’ is the required triangle.
Rate this question :